Use a dedicated "mmio-sram" and the genpool allocator instead of
open-coding SRAM allocation for DMA rings.
Keep support for legacy device trees but notify the user via a
warning to update.
Co-developed-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
v2: fix return type of mtk_dma_ring_alloc() in case of error
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 120 +++++++++++++-------
drivers/net/ethernet/mediatek/mtk_eth_soc.h | 4 +-
2 files changed, 84 insertions(+), 40 deletions(-)
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 8f55069441f4..b6a9574cf565 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -27,6 +27,7 @@
#include <net/dsa.h>
#include <net/dst_metadata.h>
#include <net/page_pool/helpers.h>
+#include <linux/genalloc.h>
#include "mtk_eth_soc.h"
#include "mtk_wed.h"
@@ -1267,6 +1268,45 @@ static void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)
return (void *)data;
}
+static bool mtk_use_legacy_sram(struct mtk_eth *eth)
+{
+ return !eth->sram_pool && MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM);
+}
+
+static void *mtk_dma_ring_alloc(struct mtk_eth *eth, size_t size,
+ dma_addr_t *dma_handle)
+{
+ void *dma_ring;
+
+ if (WARN_ON(mtk_use_legacy_sram(eth)))
+ return NULL;
+
+ if (eth->sram_pool) {
+ dma_ring = (void *)gen_pool_alloc(eth->sram_pool, size);
+ if (!dma_ring)
+ return dma_ring;
+ *dma_handle = gen_pool_virt_to_phys(eth->sram_pool,
+ (unsigned long)dma_ring);
+ } else {
+ dma_ring = dma_alloc_coherent(eth->dma_dev, size, dma_handle,
+ GFP_KERNEL);
+ }
+
+ return dma_ring;
+}
+
+static void mtk_dma_ring_free(struct mtk_eth *eth, size_t size, void *dma_ring,
+ dma_addr_t dma_handle)
+{
+ if (WARN_ON(mtk_use_legacy_sram(eth)))
+ return;
+
+ if (eth->sram_pool)
+ gen_pool_free(eth->sram_pool, (unsigned long)dma_ring, size);
+ else
+ dma_free_coherent(eth->dma_dev, size, dma_ring, dma_handle);
+}
+
/* the qdma core needs scratch memory to be setup */
static int mtk_init_fq_dma(struct mtk_eth *eth)
{
@@ -1276,13 +1316,12 @@ static int mtk_init_fq_dma(struct mtk_eth *eth)
dma_addr_t dma_addr;
int i, j, len;
- if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM))
+ if (!mtk_use_legacy_sram(eth)) {
+ eth->scratch_ring = mtk_dma_ring_alloc(eth, cnt * soc->tx.desc_size,
+ ð->phy_scratch_ring);
+ } else {
eth->scratch_ring = eth->sram_base;
- else
- eth->scratch_ring = dma_alloc_coherent(eth->dma_dev,
- cnt * soc->tx.desc_size,
- ð->phy_scratch_ring,
- GFP_KERNEL);
+ }
if (unlikely(!eth->scratch_ring))
return -ENOMEM;
@@ -2620,12 +2659,11 @@ static int mtk_tx_alloc(struct mtk_eth *eth)
if (!ring->buf)
goto no_tx_mem;
- if (MTK_HAS_CAPS(soc->caps, MTK_SRAM)) {
+ if (!mtk_use_legacy_sram(eth)) {
+ ring->dma = mtk_dma_ring_alloc(eth, ring_size * sz, &ring->phys);
+ } else {
ring->dma = eth->sram_base + soc->tx.fq_dma_size * sz;
ring->phys = eth->phy_scratch_ring + soc->tx.fq_dma_size * (dma_addr_t)sz;
- } else {
- ring->dma = dma_alloc_coherent(eth->dma_dev, ring_size * sz,
- &ring->phys, GFP_KERNEL);
}
if (!ring->dma)
@@ -2726,9 +2764,9 @@ static void mtk_tx_clean(struct mtk_eth *eth)
kfree(ring->buf);
ring->buf = NULL;
}
- if (!MTK_HAS_CAPS(soc->caps, MTK_SRAM) && ring->dma) {
- dma_free_coherent(eth->dma_dev,
- ring->dma_size * soc->tx.desc_size,
+
+ if (!mtk_use_legacy_sram(eth) && ring->dma) {
+ mtk_dma_ring_free(eth, ring->dma_size * soc->tx.desc_size,
ring->dma, ring->phys);
ring->dma = NULL;
}
@@ -2793,6 +2831,9 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
ring->dma = dma_alloc_coherent(eth->dma_dev,
rx_dma_size * eth->soc->rx.desc_size,
&ring->phys, GFP_KERNEL);
+ } else if (eth->sram_pool) {
+ ring->dma = mtk_dma_ring_alloc(eth, rx_dma_size * eth->soc->rx.desc_size,
+ &ring->phys);
} else {
struct mtk_tx_ring *tx_ring = ð->tx_ring;
@@ -2921,6 +2962,11 @@ static void mtk_rx_clean(struct mtk_eth *eth, struct mtk_rx_ring *ring, bool in_
ring->dma_size * eth->soc->rx.desc_size,
ring->dma, ring->phys);
ring->dma = NULL;
+ } else if (!mtk_use_legacy_sram(eth) && ring->dma) {
+ mtk_dma_ring_free(eth,
+ ring->dma_size * eth->soc->rx.desc_size,
+ ring->dma, ring->phys);
+ ring->dma = NULL;
}
if (ring->page_pool) {
@@ -3287,9 +3333,8 @@ static void mtk_dma_free(struct mtk_eth *eth)
netdev_tx_reset_subqueue(eth->netdev[i], j);
}
- if (!MTK_HAS_CAPS(soc->caps, MTK_SRAM) && eth->scratch_ring) {
- dma_free_coherent(eth->dma_dev,
- MTK_QDMA_RING_SIZE * soc->tx.desc_size,
+ if (!mtk_use_legacy_sram(eth) && eth->scratch_ring) {
+ mtk_dma_ring_free(eth, soc->tx.fq_dma_size * soc->tx.desc_size,
eth->scratch_ring, eth->phy_scratch_ring);
eth->scratch_ring = NULL;
eth->phy_scratch_ring = 0;
@@ -5009,7 +5054,7 @@ static int mtk_sgmii_init(struct mtk_eth *eth)
static int mtk_probe(struct platform_device *pdev)
{
- struct resource *res = NULL, *res_sram;
+ struct resource *res = NULL;
struct device_node *mac_np;
struct mtk_eth *eth;
int err, i;
@@ -5029,20 +5074,6 @@ static int mtk_probe(struct platform_device *pdev)
if (MTK_HAS_CAPS(eth->soc->caps, MTK_SOC_MT7628))
eth->ip_align = NET_IP_ALIGN;
- if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
- /* SRAM is actual memory and supports transparent access just like DRAM.
- * Hence we don't require __iomem being set and don't need to use accessor
- * functions to read from or write to SRAM.
- */
- if (mtk_is_netsys_v3_or_greater(eth)) {
- eth->sram_base = (void __force *)devm_platform_ioremap_resource(pdev, 1);
- if (IS_ERR(eth->sram_base))
- return PTR_ERR(eth->sram_base);
- } else {
- eth->sram_base = (void __force *)eth->base + MTK_ETH_SRAM_OFFSET;
- }
- }
-
if (MTK_HAS_CAPS(eth->soc->caps, MTK_36BIT_DMA)) {
err = dma_set_mask(&pdev->dev, DMA_BIT_MASK(36));
if (!err)
@@ -5117,16 +5148,27 @@ static int mtk_probe(struct platform_device *pdev)
err = -EINVAL;
goto err_destroy_sgmii;
}
+
if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
- if (mtk_is_netsys_v3_or_greater(eth)) {
- res_sram = platform_get_resource(pdev, IORESOURCE_MEM, 1);
- if (!res_sram) {
- err = -EINVAL;
- goto err_destroy_sgmii;
+ eth->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
+ if (!eth->sram_pool) {
+ if (!mtk_is_netsys_v3_or_greater(eth)) {
+ /*
+ * Legacy support for missing 'sram' node in DT.
+ * SRAM is actual memory and supports transparent access
+ * just like DRAM. Hence we don't require __iomem being
+ * set and don't need to use accessor functions to read from
+ * or write to SRAM.
+ */
+ eth->sram_base = (void __force *)eth->base +
+ MTK_ETH_SRAM_OFFSET;
+ eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
+ dev_warn(&pdev->dev,
+ "legacy DT: using hard-coded SRAM offset.\n");
+ } else {
+ dev_err(&pdev->dev, "Could not get SRAM pool\n");
+ return -ENODEV;
}
- eth->phy_scratch_ring = res_sram->start;
- } else {
- eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
}
}
}
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index 1ad9075a9b69..0104659e37f0 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -1245,7 +1245,8 @@ struct mtk_soc_data {
* @dev: The device pointer
* @dma_dev: The device pointer used for dma mapping/alloc
* @base: The mapped register i/o base
- * @sram_base: The mapped SRAM base
+ * @sram_base: The mapped SRAM base (deprecated)
+ * @sram_pool: Pointer to SRAM pool used for DMA descriptor rings
* @page_lock: Make sure that register operations are atomic
* @tx_irq__lock: Make sure that IRQ register operations are atomic
* @rx_irq__lock: Make sure that IRQ register operations are atomic
@@ -1292,6 +1293,7 @@ struct mtk_eth {
struct device *dma_dev;
void __iomem *base;
void *sram_base;
+ struct gen_pool *sram_pool;
spinlock_t page_lock;
spinlock_t tx_irq_lock;
spinlock_t rx_irq_lock;
--
2.50.0On Sun, Jun 29, 2025 at 11:22:44PM +0100, Daniel Golle wrote:
> Use a dedicated "mmio-sram" and the genpool allocator instead of
> open-coding SRAM allocation for DMA rings.
> Keep support for legacy device trees but notify the user via a
> warning to update.
>
> Co-developed-by: Frank Wunderlich <frank-w@public-files.de>
> Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> Signed-off-by: Daniel Golle <daniel@makrotopia.org>
> ---
> v2: fix return type of mtk_dma_ring_alloc() in case of error
>
> drivers/net/ethernet/mediatek/mtk_eth_soc.c | 120 +++++++++++++-------
> drivers/net/ethernet/mediatek/mtk_eth_soc.h | 4 +-
> 2 files changed, 84 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
...
> @@ -5117,16 +5148,27 @@ static int mtk_probe(struct platform_device *pdev)
> err = -EINVAL;
> goto err_destroy_sgmii;
> }
> +
> if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
> - if (mtk_is_netsys_v3_or_greater(eth)) {
> - res_sram = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> - if (!res_sram) {
> - err = -EINVAL;
> - goto err_destroy_sgmii;
> + eth->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
> + if (!eth->sram_pool) {
> + if (!mtk_is_netsys_v3_or_greater(eth)) {
> + /*
> + * Legacy support for missing 'sram' node in DT.
> + * SRAM is actual memory and supports transparent access
> + * just like DRAM. Hence we don't require __iomem being
> + * set and don't need to use accessor functions to read from
> + * or write to SRAM.
> + */
> + eth->sram_base = (void __force *)eth->base +
> + MTK_ETH_SRAM_OFFSET;
> + eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
> + dev_warn(&pdev->dev,
> + "legacy DT: using hard-coded SRAM offset.\n");
> + } else {
> + dev_err(&pdev->dev, "Could not get SRAM pool\n");
> + return -ENODEV;
Hi Daniel,
Rather than returning, should this
jump to err_destroy_sgmii to avoid leaking resources?
Flagged by Smatch.
> }
> - eth->phy_scratch_ring = res_sram->start;
> - } else {
> - eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
> }
> }
> }
On Mon, Jun 30, 2025 at 05:29:59PM +0100, Simon Horman wrote:
> On Sun, Jun 29, 2025 at 11:22:44PM +0100, Daniel Golle wrote:
> > Use a dedicated "mmio-sram" and the genpool allocator instead of
> > open-coding SRAM allocation for DMA rings.
> > Keep support for legacy device trees but notify the user via a
> > warning to update.
> >
> > Co-developed-by: Frank Wunderlich <frank-w@public-files.de>
> > Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> > Signed-off-by: Daniel Golle <daniel@makrotopia.org>
> > ---
> > v2: fix return type of mtk_dma_ring_alloc() in case of error
> >
> > drivers/net/ethernet/mediatek/mtk_eth_soc.c | 120 +++++++++++++-------
> > drivers/net/ethernet/mediatek/mtk_eth_soc.h | 4 +-
> > 2 files changed, 84 insertions(+), 40 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
>
> ...
>
> > @@ -5117,16 +5148,27 @@ static int mtk_probe(struct platform_device *pdev)
> > err = -EINVAL;
> > goto err_destroy_sgmii;
> > }
> > +
> > if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
> > - if (mtk_is_netsys_v3_or_greater(eth)) {
> > - res_sram = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > - if (!res_sram) {
> > - err = -EINVAL;
> > - goto err_destroy_sgmii;
> > + eth->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
> > + if (!eth->sram_pool) {
> > + if (!mtk_is_netsys_v3_or_greater(eth)) {
> > + /*
> > + * Legacy support for missing 'sram' node in DT.
> > + * SRAM is actual memory and supports transparent access
> > + * just like DRAM. Hence we don't require __iomem being
> > + * set and don't need to use accessor functions to read from
> > + * or write to SRAM.
> > + */
> > + eth->sram_base = (void __force *)eth->base +
> > + MTK_ETH_SRAM_OFFSET;
> > + eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
> > + dev_warn(&pdev->dev,
> > + "legacy DT: using hard-coded SRAM offset.\n");
> > + } else {
> > + dev_err(&pdev->dev, "Could not get SRAM pool\n");
> > + return -ENODEV;
>
> Hi Daniel,
>
> Rather than returning, should this
> jump to err_destroy_sgmii to avoid leaking resources?
Yes, you are right. I'll fix that in v3.
On Mon, Jun 30, 2025 at 07:19:42PM +0100, Daniel Golle wrote:
> On Mon, Jun 30, 2025 at 05:29:59PM +0100, Simon Horman wrote:
> > On Sun, Jun 29, 2025 at 11:22:44PM +0100, Daniel Golle wrote:
> > > Use a dedicated "mmio-sram" and the genpool allocator instead of
> > > open-coding SRAM allocation for DMA rings.
> > > Keep support for legacy device trees but notify the user via a
> > > warning to update.
> > >
> > > Co-developed-by: Frank Wunderlich <frank-w@public-files.de>
> > > Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> > > Signed-off-by: Daniel Golle <daniel@makrotopia.org>
> > > ---
> > > v2: fix return type of mtk_dma_ring_alloc() in case of error
> > >
> > > drivers/net/ethernet/mediatek/mtk_eth_soc.c | 120 +++++++++++++-------
> > > drivers/net/ethernet/mediatek/mtk_eth_soc.h | 4 +-
> > > 2 files changed, 84 insertions(+), 40 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> >
> > ...
> >
> > > @@ -5117,16 +5148,27 @@ static int mtk_probe(struct platform_device *pdev)
> > > err = -EINVAL;
> > > goto err_destroy_sgmii;
> > > }
> > > +
> > > if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM)) {
> > > - if (mtk_is_netsys_v3_or_greater(eth)) {
> > > - res_sram = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > > - if (!res_sram) {
> > > - err = -EINVAL;
> > > - goto err_destroy_sgmii;
> > > + eth->sram_pool = of_gen_pool_get(pdev->dev.of_node, "sram", 0);
> > > + if (!eth->sram_pool) {
> > > + if (!mtk_is_netsys_v3_or_greater(eth)) {
> > > + /*
> > > + * Legacy support for missing 'sram' node in DT.
> > > + * SRAM is actual memory and supports transparent access
> > > + * just like DRAM. Hence we don't require __iomem being
> > > + * set and don't need to use accessor functions to read from
> > > + * or write to SRAM.
> > > + */
> > > + eth->sram_base = (void __force *)eth->base +
> > > + MTK_ETH_SRAM_OFFSET;
> > > + eth->phy_scratch_ring = res->start + MTK_ETH_SRAM_OFFSET;
> > > + dev_warn(&pdev->dev,
> > > + "legacy DT: using hard-coded SRAM offset.\n");
> > > + } else {
> > > + dev_err(&pdev->dev, "Could not get SRAM pool\n");
> > > + return -ENODEV;
> >
> > Hi Daniel,
> >
> > Rather than returning, should this
> > jump to err_destroy_sgmii to avoid leaking resources?
>
> Yes, you are right. I'll fix that in v3.
Thanks.
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