Add Interconnect framework support to dynamically set the DRAM
bandwidth from different clients. Both the MC and EMC drivers are
added as ICC providers. The path for any request is:
MC-Client[1-n] -> MC -> EMC -> EMEM/DRAM
MC client's request for bandwidth will go to the MC driver which
passes the client request info like BPMP Client ID, Client type
and the Bandwidth to the BPMP-FW. The final DRAM freq to achieve
the requested bandwidth is set by the BPMP-FW based on the passed
parameters.
Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
drivers/memory/tegra/mc.c | 5 +
drivers/memory/tegra/tegra186-emc.c | 130 ++++++++++++++++++++++++++
drivers/memory/tegra/tegra234.c | 138 +++++++++++++++++++++++++++-
include/linux/tegra-icc.h | 65 +++++++++++++
include/soc/tegra/mc.h | 7 ++
5 files changed, 344 insertions(+), 1 deletion(-)
create mode 100644 include/linux/tegra-icc.h
diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
index 9082b6c3763d..983455b1f98d 100644
--- a/drivers/memory/tegra/mc.c
+++ b/drivers/memory/tegra/mc.c
@@ -15,6 +15,7 @@
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/sort.h>
+#include <linux/tegra-icc.h>
#include <soc/tegra/fuse.h>
@@ -792,6 +793,8 @@ static int tegra_mc_interconnect_setup(struct tegra_mc *mc)
mc->provider.data = &mc->provider;
mc->provider.set = mc->soc->icc_ops->set;
mc->provider.aggregate = mc->soc->icc_ops->aggregate;
+ mc->provider.get_bw = mc->soc->icc_ops->get_bw;
+ mc->provider.xlate = mc->soc->icc_ops->xlate;
mc->provider.xlate_extended = mc->soc->icc_ops->xlate_extended;
icc_provider_init(&mc->provider);
@@ -824,6 +827,8 @@ static int tegra_mc_interconnect_setup(struct tegra_mc *mc)
err = icc_link_create(node, TEGRA_ICC_MC);
if (err)
goto remove_nodes;
+
+ node->data = (struct tegra_mc_client *)&(mc->soc->clients[i]);
}
err = icc_provider_register(&mc->provider);
diff --git a/drivers/memory/tegra/tegra186-emc.c b/drivers/memory/tegra/tegra186-emc.c
index e935ad4e95b6..0aa6c049aa43 100644
--- a/drivers/memory/tegra/tegra186-emc.c
+++ b/drivers/memory/tegra/tegra186-emc.c
@@ -7,9 +7,11 @@
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
+#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <soc/tegra/bpmp.h>
+#include "mc.h"
struct tegra186_emc_dvfs {
unsigned long latency;
@@ -29,8 +31,15 @@ struct tegra186_emc {
unsigned long min_rate;
unsigned long max_rate;
} debugfs;
+
+ struct icc_provider provider;
};
+static inline struct tegra186_emc *to_tegra186_emc(struct icc_provider *provider)
+{
+ return container_of(provider, struct tegra186_emc, provider);
+}
+
/*
* debugfs interface
*
@@ -146,8 +155,102 @@ DEFINE_DEBUGFS_ATTRIBUTE(tegra186_emc_debug_max_rate_fops,
tegra186_emc_debug_max_rate_get,
tegra186_emc_debug_max_rate_set, "%llu\n");
+/*
+ * tegra_emc_icc_set_bw() - Set BW api for EMC provider
+ * @src: ICC node for External Memory Controller (EMC)
+ * @dst: ICC node for External Memory (DRAM)
+ *
+ * Do nothing here as info to BPMP-FW is now passed in the BW set function
+ * of the MC driver. BPMP-FW sets the final Freq based on the passed values.
+ */
+static int tegra_emc_icc_set_bw(struct icc_node *src, struct icc_node *dst)
+{
+ return 0;
+}
+
+static struct icc_node *
+tegra_emc_of_icc_xlate(struct of_phandle_args *spec, void *data)
+{
+ struct icc_provider *provider = data;
+ struct icc_node *node;
+
+ /* External Memory is the only possible ICC route */
+ list_for_each_entry(node, &provider->nodes, node_list) {
+ if (node->id != TEGRA_ICC_EMEM)
+ continue;
+
+ return node;
+ }
+
+ return ERR_PTR(-EPROBE_DEFER);
+}
+
+static int tegra_emc_icc_get_init_bw(struct icc_node *node, u32 *avg, u32 *peak)
+{
+ *avg = 0;
+ *peak = 0;
+
+ return 0;
+}
+
+static int tegra_emc_interconnect_init(struct tegra186_emc *emc)
+{
+ struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent);
+ const struct tegra_mc_soc *soc = mc->soc;
+ struct icc_node *node;
+ int err;
+
+ emc->provider.dev = emc->dev;
+ emc->provider.set = tegra_emc_icc_set_bw;
+ emc->provider.data = &emc->provider;
+ emc->provider.aggregate = soc->icc_ops->aggregate;
+ emc->provider.xlate = tegra_emc_of_icc_xlate;
+ emc->provider.get_bw = tegra_emc_icc_get_init_bw;
+
+ icc_provider_init(&emc->provider);
+
+ /* create External Memory Controller node */
+ node = icc_node_create(TEGRA_ICC_EMC);
+ if (IS_ERR(node)) {
+ err = PTR_ERR(node);
+ goto err_msg;
+ }
+
+ node->name = "External Memory Controller";
+ icc_node_add(node, &emc->provider);
+
+ /* link External Memory Controller to External Memory (DRAM) */
+ err = icc_link_create(node, TEGRA_ICC_EMEM);
+ if (err)
+ goto remove_nodes;
+
+ /* create External Memory node */
+ node = icc_node_create(TEGRA_ICC_EMEM);
+ if (IS_ERR(node)) {
+ err = PTR_ERR(node);
+ goto remove_nodes;
+ }
+
+ node->name = "External Memory (DRAM)";
+ icc_node_add(node, &emc->provider);
+
+ err = icc_provider_register(&emc->provider);
+ if (err)
+ goto remove_nodes;
+
+ return 0;
+
+remove_nodes:
+ icc_nodes_remove(&emc->provider);
+err_msg:
+ dev_err(emc->dev, "failed to initialize ICC: %d\n", err);
+
+ return err;
+}
+
static int tegra186_emc_probe(struct platform_device *pdev)
{
+ struct tegra_mc *mc = dev_get_drvdata(pdev->dev.parent);
struct mrq_emc_dvfs_latency_response response;
struct tegra_bpmp_message msg;
struct tegra186_emc *emc;
@@ -236,6 +339,29 @@ static int tegra186_emc_probe(struct platform_device *pdev)
debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
emc, &tegra186_emc_debug_max_rate_fops);
+ if (mc && mc->soc->icc_ops) {
+ /*
+ * Initialize the ICC even if BPMP-FW doesn't support 'MRQ_BWMGR_INT'.
+ * Use the flag 'mc->bwmgr_mrq_supported' within MC driver and return
+ * EINVAL instead of passing the request to BPMP-FW later when the BW
+ * request is made by client with 'icc_set_bw()' call.
+ */
+ err = tegra_emc_interconnect_init(emc);
+ if (err)
+ goto put_bpmp;
+
+ if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
+ mc->bwmgr_mrq_supported = true;
+
+ /*
+ * MC driver probe can't get BPMP reference as it gets probed
+ * earlier than BPMP. So, save the BPMP ref got from the EMC
+ * DT node in the mc->bpmp and use it in MC's icc_set hook.
+ */
+ mc->bpmp = emc->bpmp;
+ }
+ }
+
return 0;
put_bpmp:
@@ -245,9 +371,12 @@ static int tegra186_emc_probe(struct platform_device *pdev)
static int tegra186_emc_remove(struct platform_device *pdev)
{
+ struct tegra_mc *mc = dev_get_drvdata(pdev->dev.parent);
struct tegra186_emc *emc = platform_get_drvdata(pdev);
debugfs_remove_recursive(emc->debugfs.root);
+
+ mc->bpmp = NULL;
tegra_bpmp_put(emc->bpmp);
return 0;
@@ -272,6 +401,7 @@ static struct platform_driver tegra186_emc_driver = {
.name = "tegra186-emc",
.of_match_table = tegra186_emc_of_match,
.suppress_bind_attrs = true,
+ .sync_state = icc_sync_state,
},
.probe = tegra186_emc_probe,
.remove = tegra186_emc_remove,
diff --git a/drivers/memory/tegra/tegra234.c b/drivers/memory/tegra/tegra234.c
index 02dcc5748bba..56d911926d54 100644
--- a/drivers/memory/tegra/tegra234.c
+++ b/drivers/memory/tegra/tegra234.c
@@ -1,18 +1,23 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
- * Copyright (C) 2021-2022, NVIDIA CORPORATION. All rights reserved.
+ * Copyright (C) 2022-2023, NVIDIA CORPORATION. All rights reserved.
*/
#include <soc/tegra/mc.h>
#include <dt-bindings/memory/tegra234-mc.h>
+#include <linux/interconnect.h>
+#include <linux/tegra-icc.h>
+#include <soc/tegra/bpmp.h>
#include "mc.h"
static const struct tegra_mc_client tegra234_mc_clients[] = {
{
.id = TEGRA234_MEMORY_CLIENT_MGBEARD,
.name = "mgbeard",
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_MGBE,
.regs = {
.sid = {
@@ -23,6 +28,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_MGBEBRD,
.name = "mgbebrd",
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_MGBE_VF1,
.regs = {
.sid = {
@@ -33,6 +40,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_MGBECRD,
.name = "mgbecrd",
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_MGBE_VF2,
.regs = {
.sid = {
@@ -43,6 +52,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_MGBEDRD,
.name = "mgbedrd",
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_MGBE_VF3,
.regs = {
.sid = {
@@ -52,6 +63,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
},
}, {
.id = TEGRA234_MEMORY_CLIENT_MGBEAWR,
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.name = "mgbeawr",
.sid = TEGRA234_SID_MGBE,
.regs = {
@@ -63,6 +76,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_MGBEBWR,
.name = "mgbebwr",
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_MGBE_VF1,
.regs = {
.sid = {
@@ -73,6 +88,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_MGBECWR,
.name = "mgbecwr",
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_MGBE_VF2,
.regs = {
.sid = {
@@ -83,6 +100,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_SDMMCRAB,
.name = "sdmmcrab",
+ .bpmp_id = TEGRA_ICC_BPMP_SDMMC_4,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_SDMMC4,
.regs = {
.sid = {
@@ -93,6 +112,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_MGBEDWR,
.name = "mgbedwr",
+ .bpmp_id = TEGRA_ICC_BPMP_EQOS,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_MGBE_VF3,
.regs = {
.sid = {
@@ -103,6 +124,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_SDMMCWAB,
.name = "sdmmcwab",
+ .bpmp_id = TEGRA_ICC_BPMP_SDMMC_4,
+ .type = TEGRA_ICC_NISO,
.sid = TEGRA234_SID_SDMMC4,
.regs = {
.sid = {
@@ -153,6 +176,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_APEDMAR,
.name = "apedmar",
+ .bpmp_id = TEGRA_ICC_BPMP_APEDMA,
+ .type = TEGRA_ICC_ISO_AUDIO,
.sid = TEGRA234_SID_APE,
.regs = {
.sid = {
@@ -163,6 +188,8 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
}, {
.id = TEGRA234_MEMORY_CLIENT_APEDMAW,
.name = "apedmaw",
+ .bpmp_id = TEGRA_ICC_BPMP_APEDMA,
+ .type = TEGRA_ICC_ISO_AUDIO,
.sid = TEGRA234_SID_APE,
.regs = {
.sid = {
@@ -333,6 +360,114 @@ static const struct tegra_mc_client tegra234_mc_clients[] = {
},
};
+/*
+ * tegra234_mc_icc_set() - Pass MC client info to the BPMP-FW
+ * @src: ICC node for Memory Controller's (MC) Client
+ * @dst: ICC node for Memory Controller (MC)
+ *
+ * Passing the current request info from the MC to the BPMP-FW where
+ * LA and PTSA registers are accessed and the final EMC freq is set
+ * based on client_id, type, latency and bandwidth.
+ * icc_set_bw() makes set_bw calls for both MC and EMC providers in
+ * sequence. Both the calls are protected by 'mutex_lock(&icc_lock)'.
+ * So, the data passed won't be updated by concurrent set calls from
+ * other clients.
+ */
+static int tegra234_mc_icc_set(struct icc_node *src, struct icc_node *dst)
+{
+ struct tegra_mc *mc = icc_provider_to_tegra_mc(dst->provider);
+ struct mrq_bwmgr_int_request bwmgr_req = { 0 };
+ struct mrq_bwmgr_int_response bwmgr_resp = { 0 };
+ const struct tegra_mc_client *pclient = src->data;
+ struct tegra_bpmp_message msg;
+ int ret;
+
+ /*
+ * Same Src and Dst node will happen during boot from icc_node_add().
+ * This can be used to pre-initialize and set bandwidth for all clients
+ * before their drivers are loaded. We are skipping this case as for us,
+ * the pre-initialization already happened in Bootloader(MB2) and BPMP-FW.
+ */
+ if (src->id == dst->id)
+ return 0;
+
+ if (!mc->bwmgr_mrq_supported)
+ return -EINVAL;
+
+ if (!mc->bpmp) {
+ dev_err(mc->dev, "BPMP reference NULL\n");
+ return -ENOENT;
+ }
+
+ if (pclient->type == TEGRA_ICC_NISO)
+ bwmgr_req.bwmgr_calc_set_req.niso_bw = src->avg_bw;
+ else
+ bwmgr_req.bwmgr_calc_set_req.iso_bw = src->avg_bw;
+
+ bwmgr_req.bwmgr_calc_set_req.client_id = pclient->bpmp_id;
+
+ bwmgr_req.cmd = CMD_BWMGR_INT_CALC_AND_SET;
+ bwmgr_req.bwmgr_calc_set_req.mc_floor = src->peak_bw;
+ bwmgr_req.bwmgr_calc_set_req.floor_unit = BWMGR_INT_UNIT_KBPS;
+
+ memset(&msg, 0, sizeof(msg));
+ msg.mrq = MRQ_BWMGR_INT;
+ msg.tx.data = &bwmgr_req;
+ msg.tx.size = sizeof(bwmgr_req);
+ msg.rx.data = &bwmgr_resp;
+ msg.rx.size = sizeof(bwmgr_resp);
+
+ ret = tegra_bpmp_transfer(mc->bpmp, &msg);
+ if (ret < 0) {
+ dev_err(mc->dev, "BPMP transfer failed: %d\n", ret);
+ goto error;
+ }
+ if (msg.rx.ret < 0) {
+ pr_err("failed to set bandwidth for %u: %d\n",
+ bwmgr_req.bwmgr_calc_set_req.client_id, msg.rx.ret);
+ ret = -EINVAL;
+ }
+
+error:
+ return ret;
+}
+
+static struct icc_node*
+tegra234_mc_of_icc_xlate(struct of_phandle_args *spec, void *data)
+{
+ struct tegra_mc *mc = icc_provider_to_tegra_mc(data);
+ unsigned int cl_id = spec->args[0];
+ struct icc_node *node;
+
+ list_for_each_entry(node, &mc->provider.nodes, node_list) {
+ if (node->id != cl_id)
+ continue;
+
+ return node;
+ }
+
+ /*
+ * If a client driver calls devm_of_icc_get() before the MC driver
+ * is probed, then return EPROBE_DEFER to the client driver.
+ */
+ return ERR_PTR(-EPROBE_DEFER);
+}
+
+static int tegra234_mc_icc_get_init_bw(struct icc_node *node, u32 *avg, u32 *peak)
+{
+ *avg = 0;
+ *peak = 0;
+
+ return 0;
+}
+
+static const struct tegra_mc_icc_ops tegra234_mc_icc_ops = {
+ .xlate = tegra234_mc_of_icc_xlate,
+ .aggregate = icc_std_aggregate,
+ .get_bw = tegra234_mc_icc_get_init_bw,
+ .set = tegra234_mc_icc_set,
+};
+
const struct tegra_mc_soc tegra234_mc_soc = {
.num_clients = ARRAY_SIZE(tegra234_mc_clients),
.clients = tegra234_mc_clients,
@@ -345,6 +480,7 @@ const struct tegra_mc_soc tegra234_mc_soc = {
MC_INT_SECURITY_VIOLATION | MC_INT_DECERR_EMEM,
.has_addr_hi_reg = true,
.ops = &tegra186_mc_ops,
+ .icc_ops = &tegra234_mc_icc_ops,
.ch_intmask = 0x0000ff00,
.global_intstatus_channel_shift = 8,
/*
diff --git a/include/linux/tegra-icc.h b/include/linux/tegra-icc.h
new file mode 100644
index 000000000000..4b4d4bee290c
--- /dev/null
+++ b/include/linux/tegra-icc.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2022-2023 NVIDIA CORPORATION. All rights reserved.
+ */
+
+#ifndef LINUX_TEGRA_ICC_H
+#define LINUX_TEGRA_ICC_H
+
+enum tegra_icc_client_type {
+ TEGRA_ICC_NONE,
+ TEGRA_ICC_NISO,
+ TEGRA_ICC_ISO_DISPLAY,
+ TEGRA_ICC_ISO_VI,
+ TEGRA_ICC_ISO_AUDIO,
+ TEGRA_ICC_ISO_VIFAL,
+};
+
+/* ICC ID's for MC client's used in BPMP */
+#define TEGRA_ICC_BPMP_DEBUG 1
+#define TEGRA_ICC_BPMP_CPU_CLUSTER0 2
+#define TEGRA_ICC_BPMP_CPU_CLUSTER1 3
+#define TEGRA_ICC_BPMP_CPU_CLUSTER2 4
+#define TEGRA_ICC_BPMP_GPU 5
+#define TEGRA_ICC_BPMP_CACTMON 6
+#define TEGRA_ICC_BPMP_DISPLAY 7
+#define TEGRA_ICC_BPMP_VI 8
+#define TEGRA_ICC_BPMP_EQOS 9
+#define TEGRA_ICC_BPMP_PCIE_0 10
+#define TEGRA_ICC_BPMP_PCIE_1 11
+#define TEGRA_ICC_BPMP_PCIE_2 12
+#define TEGRA_ICC_BPMP_PCIE_3 13
+#define TEGRA_ICC_BPMP_PCIE_4 14
+#define TEGRA_ICC_BPMP_PCIE_5 15
+#define TEGRA_ICC_BPMP_PCIE_6 16
+#define TEGRA_ICC_BPMP_PCIE_7 17
+#define TEGRA_ICC_BPMP_PCIE_8 18
+#define TEGRA_ICC_BPMP_PCIE_9 19
+#define TEGRA_ICC_BPMP_PCIE_10 20
+#define TEGRA_ICC_BPMP_DLA_0 21
+#define TEGRA_ICC_BPMP_DLA_1 22
+#define TEGRA_ICC_BPMP_SDMMC_1 23
+#define TEGRA_ICC_BPMP_SDMMC_2 24
+#define TEGRA_ICC_BPMP_SDMMC_3 25
+#define TEGRA_ICC_BPMP_SDMMC_4 26
+#define TEGRA_ICC_BPMP_NVDEC 27
+#define TEGRA_ICC_BPMP_NVENC 28
+#define TEGRA_ICC_BPMP_NVJPG_0 29
+#define TEGRA_ICC_BPMP_NVJPG_1 30
+#define TEGRA_ICC_BPMP_OFAA 31
+#define TEGRA_ICC_BPMP_XUSB_HOST 32
+#define TEGRA_ICC_BPMP_XUSB_DEV 33
+#define TEGRA_ICC_BPMP_TSEC 34
+#define TEGRA_ICC_BPMP_VIC 35
+#define TEGRA_ICC_BPMP_APE 36
+#define TEGRA_ICC_BPMP_APEDMA 37
+#define TEGRA_ICC_BPMP_SE 38
+#define TEGRA_ICC_BPMP_ISP 39
+#define TEGRA_ICC_BPMP_HDA 40
+#define TEGRA_ICC_BPMP_VIFAL 41
+#define TEGRA_ICC_BPMP_VI2FAL 42
+#define TEGRA_ICC_BPMP_VI2 43
+#define TEGRA_ICC_BPMP_RCE 44
+#define TEGRA_ICC_BPMP_PVA 45
+
+#endif /* LINUX_TEGRA_ICC_H */
diff --git a/include/soc/tegra/mc.h b/include/soc/tegra/mc.h
index 51a2263e1bc5..900d88b26fae 100644
--- a/include/soc/tegra/mc.h
+++ b/include/soc/tegra/mc.h
@@ -13,6 +13,7 @@
#include <linux/irq.h>
#include <linux/reset-controller.h>
#include <linux/types.h>
+#include <linux/tegra-icc.h>
struct clk;
struct device;
@@ -26,6 +27,8 @@ struct tegra_mc_timing {
struct tegra_mc_client {
unsigned int id;
+ unsigned int bpmp_id;
+ enum tegra_icc_client_type type;
const char *name;
/*
* For Tegra210 and earlier, this is the SWGROUP ID used for IOVA translations in the
@@ -166,8 +169,10 @@ struct tegra_mc_icc_ops {
int (*set)(struct icc_node *src, struct icc_node *dst);
int (*aggregate)(struct icc_node *node, u32 tag, u32 avg_bw,
u32 peak_bw, u32 *agg_avg, u32 *agg_peak);
+ struct icc_node* (*xlate)(struct of_phandle_args *spec, void *data);
struct icc_node_data *(*xlate_extended)(struct of_phandle_args *spec,
void *data);
+ int (*get_bw)(struct icc_node *node, u32 *avg, u32 *peak);
};
struct tegra_mc_ops {
@@ -214,6 +219,7 @@ struct tegra_mc_soc {
};
struct tegra_mc {
+ struct tegra_bpmp *bpmp;
struct device *dev;
struct tegra_smmu *smmu;
struct gart_device *gart;
@@ -229,6 +235,7 @@ struct tegra_mc {
struct tegra_mc_timing *timings;
unsigned int num_timings;
+ bool bwmgr_mrq_supported;
struct reset_controller_dev reset;
struct icc_provider provider;
--
2.17.1On 24/04/2023 15:13, Sumit Gupta wrote:
> Add Interconnect framework support to dynamically set the DRAM
> bandwidth from different clients. Both the MC and EMC drivers are
> added as ICC providers. The path for any request is:
> MC-Client[1-n] -> MC -> EMC -> EMEM/DRAM
>
Thank you for your patch. There is something to discuss/improve.
> +static int tegra_emc_interconnect_init(struct tegra186_emc *emc)
> +{
> + struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent);
> + const struct tegra_mc_soc *soc = mc->soc;
> + struct icc_node *node;
> + int err;
> +
> + emc->provider.dev = emc->dev;
> + emc->provider.set = tegra_emc_icc_set_bw;
> + emc->provider.data = &emc->provider;
> + emc->provider.aggregate = soc->icc_ops->aggregate;
> + emc->provider.xlate = tegra_emc_of_icc_xlate;
> + emc->provider.get_bw = tegra_emc_icc_get_init_bw;
> +
> + icc_provider_init(&emc->provider);
> +
> + /* create External Memory Controller node */
> + node = icc_node_create(TEGRA_ICC_EMC);
> + if (IS_ERR(node)) {
> + err = PTR_ERR(node);
> + goto err_msg;
> + }
> +
> + node->name = "External Memory Controller";
> + icc_node_add(node, &emc->provider);
> +
> + /* link External Memory Controller to External Memory (DRAM) */
> + err = icc_link_create(node, TEGRA_ICC_EMEM);
> + if (err)
> + goto remove_nodes;
> +
> + /* create External Memory node */
> + node = icc_node_create(TEGRA_ICC_EMEM);
> + if (IS_ERR(node)) {
> + err = PTR_ERR(node);
> + goto remove_nodes;
> + }
> +
> + node->name = "External Memory (DRAM)";
> + icc_node_add(node, &emc->provider);
> +
> + err = icc_provider_register(&emc->provider);
> + if (err)
> + goto remove_nodes;
> +
> + return 0;
> +
> +remove_nodes:
> + icc_nodes_remove(&emc->provider);
> +err_msg:
> + dev_err(emc->dev, "failed to initialize ICC: %d\n", err);
> +
> + return err;
> +}
> +
> static int tegra186_emc_probe(struct platform_device *pdev)
> {
> + struct tegra_mc *mc = dev_get_drvdata(pdev->dev.parent);
> struct mrq_emc_dvfs_latency_response response;
> struct tegra_bpmp_message msg;
> struct tegra186_emc *emc;
> @@ -236,6 +339,29 @@ static int tegra186_emc_probe(struct platform_device *pdev)
> debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
> emc, &tegra186_emc_debug_max_rate_fops);
>
> + if (mc && mc->soc->icc_ops) {
> + /*
> + * Initialize the ICC even if BPMP-FW doesn't support 'MRQ_BWMGR_INT'.
> + * Use the flag 'mc->bwmgr_mrq_supported' within MC driver and return
> + * EINVAL instead of passing the request to BPMP-FW later when the BW
> + * request is made by client with 'icc_set_bw()' call.
> + */
> + err = tegra_emc_interconnect_init(emc);
> + if (err)
> + goto put_bpmp;
> +
> + if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
> + mc->bwmgr_mrq_supported = true;
> +
> + /*
> + * MC driver probe can't get BPMP reference as it gets probed
> + * earlier than BPMP. So, save the BPMP ref got from the EMC
> + * DT node in the mc->bpmp and use it in MC's icc_set hook.
> + */
> + mc->bpmp = emc->bpmp;
This (and ()) are called without any locking. You register first the
interconnect, so set() callback can be used, right? Then set() could be
called anytime between tegra_emc_interconnect_init() and assignment
above. How do you synchronize these?
Best regards,
Krzysztof
On 24/04/23 19:18, Krzysztof Kozlowski wrote:
> External email: Use caution opening links or attachments
>
>
> On 24/04/2023 15:13, Sumit Gupta wrote:
>> Add Interconnect framework support to dynamically set the DRAM
>> bandwidth from different clients. Both the MC and EMC drivers are
>> added as ICC providers. The path for any request is:
>> MC-Client[1-n] -> MC -> EMC -> EMEM/DRAM
>>
> Thank you for your patch. There is something to discuss/improve.
>
>
>> +static int tegra_emc_interconnect_init(struct tegra186_emc *emc)
>> +{
>> + struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent);
>> + const struct tegra_mc_soc *soc = mc->soc;
>> + struct icc_node *node;
>> + int err;
>> +
>> + emc->provider.dev = emc->dev;
>> + emc->provider.set = tegra_emc_icc_set_bw;
>> + emc->provider.data = &emc->provider;
>> + emc->provider.aggregate = soc->icc_ops->aggregate;
>> + emc->provider.xlate = tegra_emc_of_icc_xlate;
>> + emc->provider.get_bw = tegra_emc_icc_get_init_bw;
>> +
>> + icc_provider_init(&emc->provider);
>> +
>> + /* create External Memory Controller node */
>> + node = icc_node_create(TEGRA_ICC_EMC);
>> + if (IS_ERR(node)) {
>> + err = PTR_ERR(node);
>> + goto err_msg;
>> + }
>> +
>> + node->name = "External Memory Controller";
>> + icc_node_add(node, &emc->provider);
>> +
>> + /* link External Memory Controller to External Memory (DRAM) */
>> + err = icc_link_create(node, TEGRA_ICC_EMEM);
>> + if (err)
>> + goto remove_nodes;
>> +
>> + /* create External Memory node */
>> + node = icc_node_create(TEGRA_ICC_EMEM);
>> + if (IS_ERR(node)) {
>> + err = PTR_ERR(node);
>> + goto remove_nodes;
>> + }
>> +
>> + node->name = "External Memory (DRAM)";
>> + icc_node_add(node, &emc->provider);
>> +
>> + err = icc_provider_register(&emc->provider);
>> + if (err)
>> + goto remove_nodes;
>> +
>> + return 0;
>> +
>> +remove_nodes:
>> + icc_nodes_remove(&emc->provider);
>> +err_msg:
>> + dev_err(emc->dev, "failed to initialize ICC: %d\n", err);
>> +
>> + return err;
>> +}
>> +
>> static int tegra186_emc_probe(struct platform_device *pdev)
>> {
>> + struct tegra_mc *mc = dev_get_drvdata(pdev->dev.parent);
>> struct mrq_emc_dvfs_latency_response response;
>> struct tegra_bpmp_message msg;
>> struct tegra186_emc *emc;
>> @@ -236,6 +339,29 @@ static int tegra186_emc_probe(struct platform_device *pdev)
>> debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
>> emc, &tegra186_emc_debug_max_rate_fops);
>>
>> + if (mc && mc->soc->icc_ops) {
>> + /*
>> + * Initialize the ICC even if BPMP-FW doesn't support 'MRQ_BWMGR_INT'.
>> + * Use the flag 'mc->bwmgr_mrq_supported' within MC driver and return
>> + * EINVAL instead of passing the request to BPMP-FW later when the BW
>> + * request is made by client with 'icc_set_bw()' call.
>> + */
>> + err = tegra_emc_interconnect_init(emc);
>> + if (err)
>> + goto put_bpmp;
>> +
>> + if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
>> + mc->bwmgr_mrq_supported = true;
>> +
>> + /*
>> + * MC driver probe can't get BPMP reference as it gets probed
>> + * earlier than BPMP. So, save the BPMP ref got from the EMC
>> + * DT node in the mc->bpmp and use it in MC's icc_set hook.
>> + */
>> + mc->bpmp = emc->bpmp;
>
> This (and ()) are called without any locking. You register first the
> interconnect, so set() callback can be used, right? Then set() could be
> called anytime between tegra_emc_interconnect_init() and assignment
> above. How do you synchronize these?
>
> Best regards,
> Krzysztof
>
Currently, the tegra234_mc_icc_set() has NULL check. So, it will give
this error.
if (!mc->bpmp) {
dev_err(mc->dev, "BPMP reference NULL\n");
return -ENOENT;
}
To fix, we can do the below change and swap the order. Please let me
know if this sounds fine ?
if (mc && mc->soc->icc_ops) {
if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
mc->bwmgr_mrq_supported = true;
mc->bpmp = emc->bpmp;
}
err = tegra_emc_interconnect_init(emc);
if (err)
goto put_bpmp;
}
Thank you,
Sumit Gupta
On 24/04/23 20:30, Sumit Gupta wrote:
>
>
> On 24/04/23 19:18, Krzysztof Kozlowski wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> On 24/04/2023 15:13, Sumit Gupta wrote:
>>> Add Interconnect framework support to dynamically set the DRAM
>>> bandwidth from different clients. Both the MC and EMC drivers are
>>> added as ICC providers. The path for any request is:
>>> MC-Client[1-n] -> MC -> EMC -> EMEM/DRAM
>>>
>> Thank you for your patch. There is something to discuss/improve.
>>
>>
>>> +static int tegra_emc_interconnect_init(struct tegra186_emc *emc)
>>> +{
>>> + struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent);
>>> + const struct tegra_mc_soc *soc = mc->soc;
>>> + struct icc_node *node;
>>> + int err;
>>> +
>>> + emc->provider.dev = emc->dev;
>>> + emc->provider.set = tegra_emc_icc_set_bw;
>>> + emc->provider.data = &emc->provider;
>>> + emc->provider.aggregate = soc->icc_ops->aggregate;
>>> + emc->provider.xlate = tegra_emc_of_icc_xlate;
>>> + emc->provider.get_bw = tegra_emc_icc_get_init_bw;
>>> +
>>> + icc_provider_init(&emc->provider);
>>> +
>>> + /* create External Memory Controller node */
>>> + node = icc_node_create(TEGRA_ICC_EMC);
>>> + if (IS_ERR(node)) {
>>> + err = PTR_ERR(node);
>>> + goto err_msg;
>>> + }
>>> +
>>> + node->name = "External Memory Controller";
>>> + icc_node_add(node, &emc->provider);
>>> +
>>> + /* link External Memory Controller to External Memory (DRAM) */
>>> + err = icc_link_create(node, TEGRA_ICC_EMEM);
>>> + if (err)
>>> + goto remove_nodes;
>>> +
>>> + /* create External Memory node */
>>> + node = icc_node_create(TEGRA_ICC_EMEM);
>>> + if (IS_ERR(node)) {
>>> + err = PTR_ERR(node);
>>> + goto remove_nodes;
>>> + }
>>> +
>>> + node->name = "External Memory (DRAM)";
>>> + icc_node_add(node, &emc->provider);
>>> +
>>> + err = icc_provider_register(&emc->provider);
>>> + if (err)
>>> + goto remove_nodes;
>>> +
>>> + return 0;
>>> +
>>> +remove_nodes:
>>> + icc_nodes_remove(&emc->provider);
>>> +err_msg:
>>> + dev_err(emc->dev, "failed to initialize ICC: %d\n", err);
>>> +
>>> + return err;
>>> +}
>>> +
>>> static int tegra186_emc_probe(struct platform_device *pdev)
>>> {
>>> + struct tegra_mc *mc = dev_get_drvdata(pdev->dev.parent);
>>> struct mrq_emc_dvfs_latency_response response;
>>> struct tegra_bpmp_message msg;
>>> struct tegra186_emc *emc;
>>> @@ -236,6 +339,29 @@ static int tegra186_emc_probe(struct
>>> platform_device *pdev)
>>> debugfs_create_file("max_rate", S_IRUGO | S_IWUSR,
>>> emc->debugfs.root,
>>> emc, &tegra186_emc_debug_max_rate_fops);
>>>
>>> + if (mc && mc->soc->icc_ops) {
>>> + /*
>>> + * Initialize the ICC even if BPMP-FW doesn't support
>>> 'MRQ_BWMGR_INT'.
>>> + * Use the flag 'mc->bwmgr_mrq_supported' within MC
>>> driver and return
>>> + * EINVAL instead of passing the request to BPMP-FW
>>> later when the BW
>>> + * request is made by client with 'icc_set_bw()' call.
>>> + */
>>> + err = tegra_emc_interconnect_init(emc);
>>> + if (err)
>>> + goto put_bpmp;
>>> +
>>> + if (tegra_bpmp_mrq_is_supported(emc->bpmp,
>>> MRQ_BWMGR_INT)) {
>>> + mc->bwmgr_mrq_supported = true;
>>> +
>>> + /*
>>> + * MC driver probe can't get BPMP reference as
>>> it gets probed
>>> + * earlier than BPMP. So, save the BPMP ref got
>>> from the EMC
>>> + * DT node in the mc->bpmp and use it in MC's
>>> icc_set hook.
>>> + */
>>> + mc->bpmp = emc->bpmp;
>>
>> This (and ()) are called without any locking. You register first the
>> interconnect, so set() callback can be used, right? Then set() could be
>> called anytime between tegra_emc_interconnect_init() and assignment
>> above. How do you synchronize these?
>>
>> Best regards,
>> Krzysztof
>>
>
> Currently, the tegra234_mc_icc_set() has NULL check. So, it will give
> this error.
> if (!mc->bpmp) {
> dev_err(mc->dev, "BPMP reference NULL\n");
> return -ENOENT;
> }
>
> To fix, we can do the below change and swap the order. Please let me
> know if this sounds fine ?
> if (mc && mc->soc->icc_ops) {
> if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
> mc->bwmgr_mrq_supported = true;
> mc->bpmp = emc->bpmp;
> }
>
> err = tegra_emc_interconnect_init(emc);
> if (err)
> goto put_bpmp;
>
> }
Sorry, replied too soon. Missed setting "mc->bpmp" to NULL. Sharing new
proposed change. Please let me know if this looks OK.
if (mc && mc->soc->icc_ops) {
if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
mc->bwmgr_mrq_supported = true;
mc->bpmp = emc->bpmp;
}
err = tegra_emc_interconnect_init(emc);
if (err) {
mc->bpmp = NULL;
goto put_bpmp;
}
}
>
> Thank you,
> Sumit Gupta
On 24/04/2023 17:21, Sumit Gupta wrote:
>
>
> On 24/04/23 20:30, Sumit Gupta wrote:
>>
>>
>> On 24/04/23 19:18, Krzysztof Kozlowski wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> On 24/04/2023 15:13, Sumit Gupta wrote:
>>>> Add Interconnect framework support to dynamically set the DRAM
>>>> bandwidth from different clients. Both the MC and EMC drivers are
>>>> added as ICC providers. The path for any request is:
>>>> MC-Client[1-n] -> MC -> EMC -> EMEM/DRAM
>>>>
>>> Thank you for your patch. There is something to discuss/improve.
>>>
>>>
>>>> +static int tegra_emc_interconnect_init(struct tegra186_emc *emc)
>>>> +{
>>>> + struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent);
>>>> + const struct tegra_mc_soc *soc = mc->soc;
>>>> + struct icc_node *node;
>>>> + int err;
>>>> +
>>>> + emc->provider.dev = emc->dev;
>>>> + emc->provider.set = tegra_emc_icc_set_bw;
>>>> + emc->provider.data = &emc->provider;
>>>> + emc->provider.aggregate = soc->icc_ops->aggregate;
>>>> + emc->provider.xlate = tegra_emc_of_icc_xlate;
>>>> + emc->provider.get_bw = tegra_emc_icc_get_init_bw;
>>>> +
>>>> + icc_provider_init(&emc->provider);
>>>> +
>>>> + /* create External Memory Controller node */
>>>> + node = icc_node_create(TEGRA_ICC_EMC);
>>>> + if (IS_ERR(node)) {
>>>> + err = PTR_ERR(node);
>>>> + goto err_msg;
>>>> + }
>>>> +
>>>> + node->name = "External Memory Controller";
>>>> + icc_node_add(node, &emc->provider);
>>>> +
>>>> + /* link External Memory Controller to External Memory (DRAM) */
>>>> + err = icc_link_create(node, TEGRA_ICC_EMEM);
>>>> + if (err)
>>>> + goto remove_nodes;
>>>> +
>>>> + /* create External Memory node */
>>>> + node = icc_node_create(TEGRA_ICC_EMEM);
>>>> + if (IS_ERR(node)) {
>>>> + err = PTR_ERR(node);
>>>> + goto remove_nodes;
>>>> + }
>>>> +
>>>> + node->name = "External Memory (DRAM)";
>>>> + icc_node_add(node, &emc->provider);
>>>> +
>>>> + err = icc_provider_register(&emc->provider);
>>>> + if (err)
>>>> + goto remove_nodes;
>>>> +
>>>> + return 0;
>>>> +
>>>> +remove_nodes:
>>>> + icc_nodes_remove(&emc->provider);
>>>> +err_msg:
>>>> + dev_err(emc->dev, "failed to initialize ICC: %d\n", err);
>>>> +
>>>> + return err;
>>>> +}
>>>> +
>>>> static int tegra186_emc_probe(struct platform_device *pdev)
>>>> {
>>>> + struct tegra_mc *mc = dev_get_drvdata(pdev->dev.parent);
>>>> struct mrq_emc_dvfs_latency_response response;
>>>> struct tegra_bpmp_message msg;
>>>> struct tegra186_emc *emc;
>>>> @@ -236,6 +339,29 @@ static int tegra186_emc_probe(struct
>>>> platform_device *pdev)
>>>> debugfs_create_file("max_rate", S_IRUGO | S_IWUSR,
>>>> emc->debugfs.root,
>>>> emc, &tegra186_emc_debug_max_rate_fops);
>>>>
>>>> + if (mc && mc->soc->icc_ops) {
>>>> + /*
>>>> + * Initialize the ICC even if BPMP-FW doesn't support
>>>> 'MRQ_BWMGR_INT'.
>>>> + * Use the flag 'mc->bwmgr_mrq_supported' within MC
>>>> driver and return
>>>> + * EINVAL instead of passing the request to BPMP-FW
>>>> later when the BW
>>>> + * request is made by client with 'icc_set_bw()' call.
>>>> + */
>>>> + err = tegra_emc_interconnect_init(emc);
>>>> + if (err)
>>>> + goto put_bpmp;
>>>> +
>>>> + if (tegra_bpmp_mrq_is_supported(emc->bpmp,
>>>> MRQ_BWMGR_INT)) {
>>>> + mc->bwmgr_mrq_supported = true;
>>>> +
>>>> + /*
>>>> + * MC driver probe can't get BPMP reference as
>>>> it gets probed
>>>> + * earlier than BPMP. So, save the BPMP ref got
>>>> from the EMC
>>>> + * DT node in the mc->bpmp and use it in MC's
>>>> icc_set hook.
>>>> + */
>>>> + mc->bpmp = emc->bpmp;
>>>
>>> This (and ()) are called without any locking. You register first the
>>> interconnect, so set() callback can be used, right? Then set() could be
>>> called anytime between tegra_emc_interconnect_init() and assignment
>>> above. How do you synchronize these?
>>>
>>> Best regards,
>>> Krzysztof
>>>
>>
>> Currently, the tegra234_mc_icc_set() has NULL check. So, it will give
>> this error.
>> if (!mc->bpmp) {
How does it solve concurrent accesses and re-ordering of instructions by
compiler or CPU?
>> dev_err(mc->dev, "BPMP reference NULL\n");
>> return -ENOENT;
>> }
>>
>> To fix, we can do the below change and swap the order. Please let me
>> know if this sounds fine ?
>> if (mc && mc->soc->icc_ops) {
>> if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
>> mc->bwmgr_mrq_supported = true;
>> mc->bpmp = emc->bpmp;
>> }
>>
>> err = tegra_emc_interconnect_init(emc);
>> if (err)
>> goto put_bpmp;
>>
>> }
> Sorry, replied too soon. Missed setting "mc->bpmp" to NULL. Sharing new
> proposed change. Please let me know if this looks OK.
>
> if (mc && mc->soc->icc_ops) {
> if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
> mc->bwmgr_mrq_supported = true;
> mc->bpmp = emc->bpmp;
> }
>
> err = tegra_emc_interconnect_init(emc);
> if (err) {
> mc->bpmp = NULL;
> goto put_bpmp;
Sorry, I didn't check the code. I assume you should do it...
Best regards,
Krzysztof
On 07/05/23 14:41, Krzysztof Kozlowski wrote:
> External email: Use caution opening links or attachments
>
>
> On 24/04/2023 17:21, Sumit Gupta wrote:
>>
>>
>> On 24/04/23 20:30, Sumit Gupta wrote:
>>>
>>>
>>> On 24/04/23 19:18, Krzysztof Kozlowski wrote:
>>>> External email: Use caution opening links or attachments
>>>>
>>>>
>>>> On 24/04/2023 15:13, Sumit Gupta wrote:
>>>>> Add Interconnect framework support to dynamically set the DRAM
>>>>> bandwidth from different clients. Both the MC and EMC drivers are
>>>>> added as ICC providers. The path for any request is:
>>>>> MC-Client[1-n] -> MC -> EMC -> EMEM/DRAM
>>>>>
>>>> Thank you for your patch. There is something to discuss/improve.
>>>>
>>>>
>>>>> +static int tegra_emc_interconnect_init(struct tegra186_emc *emc)
>>>>> +{
>>>>> + struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent);
>>>>> + const struct tegra_mc_soc *soc = mc->soc;
>>>>> + struct icc_node *node;
>>>>> + int err;
>>>>> +
>>>>> + emc->provider.dev = emc->dev;
>>>>> + emc->provider.set = tegra_emc_icc_set_bw;
>>>>> + emc->provider.data = &emc->provider;
>>>>> + emc->provider.aggregate = soc->icc_ops->aggregate;
>>>>> + emc->provider.xlate = tegra_emc_of_icc_xlate;
>>>>> + emc->provider.get_bw = tegra_emc_icc_get_init_bw;
>>>>> +
>>>>> + icc_provider_init(&emc->provider);
>>>>> +
>>>>> + /* create External Memory Controller node */
>>>>> + node = icc_node_create(TEGRA_ICC_EMC);
>>>>> + if (IS_ERR(node)) {
>>>>> + err = PTR_ERR(node);
>>>>> + goto err_msg;
>>>>> + }
>>>>> +
>>>>> + node->name = "External Memory Controller";
>>>>> + icc_node_add(node, &emc->provider);
>>>>> +
>>>>> + /* link External Memory Controller to External Memory (DRAM) */
>>>>> + err = icc_link_create(node, TEGRA_ICC_EMEM);
>>>>> + if (err)
>>>>> + goto remove_nodes;
>>>>> +
>>>>> + /* create External Memory node */
>>>>> + node = icc_node_create(TEGRA_ICC_EMEM);
>>>>> + if (IS_ERR(node)) {
>>>>> + err = PTR_ERR(node);
>>>>> + goto remove_nodes;
>>>>> + }
>>>>> +
>>>>> + node->name = "External Memory (DRAM)";
>>>>> + icc_node_add(node, &emc->provider);
>>>>> +
>>>>> + err = icc_provider_register(&emc->provider);
>>>>> + if (err)
>>>>> + goto remove_nodes;
>>>>> +
>>>>> + return 0;
>>>>> +
>>>>> +remove_nodes:
>>>>> + icc_nodes_remove(&emc->provider);
>>>>> +err_msg:
>>>>> + dev_err(emc->dev, "failed to initialize ICC: %d\n", err);
>>>>> +
>>>>> + return err;
>>>>> +}
>>>>> +
>>>>> static int tegra186_emc_probe(struct platform_device *pdev)
>>>>> {
>>>>> + struct tegra_mc *mc = dev_get_drvdata(pdev->dev.parent);
>>>>> struct mrq_emc_dvfs_latency_response response;
>>>>> struct tegra_bpmp_message msg;
>>>>> struct tegra186_emc *emc;
>>>>> @@ -236,6 +339,29 @@ static int tegra186_emc_probe(struct
>>>>> platform_device *pdev)
>>>>> debugfs_create_file("max_rate", S_IRUGO | S_IWUSR,
>>>>> emc->debugfs.root,
>>>>> emc, &tegra186_emc_debug_max_rate_fops);
>>>>>
>>>>> + if (mc && mc->soc->icc_ops) {
>>>>> + /*
>>>>> + * Initialize the ICC even if BPMP-FW doesn't support
>>>>> 'MRQ_BWMGR_INT'.
>>>>> + * Use the flag 'mc->bwmgr_mrq_supported' within MC
>>>>> driver and return
>>>>> + * EINVAL instead of passing the request to BPMP-FW
>>>>> later when the BW
>>>>> + * request is made by client with 'icc_set_bw()' call.
>>>>> + */
>>>>> + err = tegra_emc_interconnect_init(emc);
>>>>> + if (err)
>>>>> + goto put_bpmp;
>>>>> +
>>>>> + if (tegra_bpmp_mrq_is_supported(emc->bpmp,
>>>>> MRQ_BWMGR_INT)) {
>>>>> + mc->bwmgr_mrq_supported = true;
>>>>> +
>>>>> + /*
>>>>> + * MC driver probe can't get BPMP reference as
>>>>> it gets probed
>>>>> + * earlier than BPMP. So, save the BPMP ref got
>>>>> from the EMC
>>>>> + * DT node in the mc->bpmp and use it in MC's
>>>>> icc_set hook.
>>>>> + */
>>>>> + mc->bpmp = emc->bpmp;
>>>>
>>>> This (and ()) are called without any locking. You register first the
>>>> interconnect, so set() callback can be used, right? Then set() could be
>>>> called anytime between tegra_emc_interconnect_init() and assignment
>>>> above. How do you synchronize these?
>>>>
>>>> Best regards,
>>>> Krzysztof
>>>>
>>>
>>> Currently, the tegra234_mc_icc_set() has NULL check. So, it will give
>>> this error.
>>> if (!mc->bpmp) {
>
> How does it solve concurrent accesses and re-ordering of instructions by
> compiler or CPU?
>
Now, the "mc->bpmp" is set before tegra_emc_interconnect_init().
So, until the EMC interconnect initializes, set() won't be
called as the devm_of_icc_get() call will fail.
Added the change in v8.
Thank you,
Sumit Gupta
>>> dev_err(mc->dev, "BPMP reference NULL\n");
>>> return -ENOENT;
>>> }
>>>
>>> To fix, we can do the below change and swap the order. Please let me
>>> know if this sounds fine ?
>>> if (mc && mc->soc->icc_ops) {
>>> if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
>>> mc->bwmgr_mrq_supported = true;
>>> mc->bpmp = emc->bpmp;
>>> }
>>>
>>> err = tegra_emc_interconnect_init(emc);
>>> if (err)
>>> goto put_bpmp;
>>>
>>> }
>> Sorry, replied too soon. Missed setting "mc->bpmp" to NULL. Sharing new
>> proposed change. Please let me know if this looks OK.
>>
>> if (mc && mc->soc->icc_ops) {
>> if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_BWMGR_INT)) {
>> mc->bwmgr_mrq_supported = true;
>> mc->bpmp = emc->bpmp;
>> }
>>
>> err = tegra_emc_interconnect_init(emc);
>> if (err) {
>> mc->bpmp = NULL;
>> goto put_bpmp;
>
> Sorry, I didn't check the code. I assume you should do it...
>
> Best regards,
> Krzysztof
>
On 09/05/2023 15:17, Sumit Gupta wrote:
>>>>>> + /*
>>>>>> + * MC driver probe can't get BPMP reference as
>>>>>> it gets probed
>>>>>> + * earlier than BPMP. So, save the BPMP ref got
>>>>>> from the EMC
>>>>>> + * DT node in the mc->bpmp and use it in MC's
>>>>>> icc_set hook.
>>>>>> + */
>>>>>> + mc->bpmp = emc->bpmp;
>>>>>
>>>>> This (and ()) are called without any locking. You register first the
>>>>> interconnect, so set() callback can be used, right? Then set() could be
>>>>> called anytime between tegra_emc_interconnect_init() and assignment
>>>>> above. How do you synchronize these?
>>>>>
>>>>> Best regards,
>>>>> Krzysztof
>>>>>
>>>>
>>>> Currently, the tegra234_mc_icc_set() has NULL check. So, it will give
>>>> this error.
>>>> if (!mc->bpmp) {
>>
>> How does it solve concurrent accesses and re-ordering of instructions by
>> compiler or CPU?
>>
>
> Now, the "mc->bpmp" is set before tegra_emc_interconnect_init().
> So, until the EMC interconnect initializes, set() won't be
> called as the devm_of_icc_get() call will fail.
What if compiler puts "mc->bpmp" assignment after
tegra_emc_interconnect_init()?
What if CPU executes above assignment also after
tegra_emc_interconnect_init()?
Considering amount of code inside tegra_emc_interconnect_init() second
case is rather unlikely, but first possible, right?
Best regards,
Krzysztof
On 09/05/23 19:06, Krzysztof Kozlowski wrote:
> External email: Use caution opening links or attachments
>
>
> On 09/05/2023 15:17, Sumit Gupta wrote:
>>>>>>> + /*
>>>>>>> + * MC driver probe can't get BPMP reference as
>>>>>>> it gets probed
>>>>>>> + * earlier than BPMP. So, save the BPMP ref got
>>>>>>> from the EMC
>>>>>>> + * DT node in the mc->bpmp and use it in MC's
>>>>>>> icc_set hook.
>>>>>>> + */
>>>>>>> + mc->bpmp = emc->bpmp;
>>>>>>
>>>>>> This (and ()) are called without any locking. You register first the
>>>>>> interconnect, so set() callback can be used, right? Then set() could be
>>>>>> called anytime between tegra_emc_interconnect_init() and assignment
>>>>>> above. How do you synchronize these?
>>>>>>
>>>>>> Best regards,
>>>>>> Krzysztof
>>>>>>
>>>>>
>>>>> Currently, the tegra234_mc_icc_set() has NULL check. So, it will give
>>>>> this error.
>>>>> if (!mc->bpmp) {
>>>
>>> How does it solve concurrent accesses and re-ordering of instructions by
>>> compiler or CPU?
>>>
>>
>> Now, the "mc->bpmp" is set before tegra_emc_interconnect_init().
>> So, until the EMC interconnect initializes, set() won't be
>> called as the devm_of_icc_get() call will fail.
>
> What if compiler puts "mc->bpmp" assignment after
> tegra_emc_interconnect_init()?
>
> What if CPU executes above assignment also after
> tegra_emc_interconnect_init()?
>
> Considering amount of code inside tegra_emc_interconnect_init() second
> case is rather unlikely, but first possible, right?
>
> Best regards,
> Krzysztof
>
Yes, for protection from compiler re-ordering I can add
barrier() after the assignment.
mc->bpmp = emc->bpmp;
barrier();
Thank you,
Sumit Gupta
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