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[PATCH v11 4/4] firmware: ti_sci: add CPU latency constraint management

Markus Schneider-Pargmann posted 4 patches 1 year, 3 months ago
There is a newer version of this series
[PATCH v11 4/4] firmware: ti_sci: add CPU latency constraint management
Posted by Markus Schneider-Pargmann 1 year, 3 months ago 
From: Kevin Hilman <khilman@baylibre.com>

During system-wide suspend, check if any of the CPUs have PM QoS
resume latency constraints set.  If so, set TI SCI constraint.

TI SCI has a single system-wide latency constraint, so use the max of
any of the CPU latencies as the system-wide value.

Note: DM firmware clears all constraints at resume time, so
constraints need to be checked/updated/sent at each system suspend.

Co-developed-by: Vibhore Vardhan <vibhore@ti.com>
Signed-off-by: Vibhore Vardhan <vibhore@ti.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/firmware/ti_sci.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
index 8482b7077eef..d5d64e5ffbd7 100644
--- a/drivers/firmware/ti_sci.c
+++ b/drivers/firmware/ti_sci.c
@@ -10,6 +10,7 @@
 #define pr_fmt(fmt) "%s: " fmt, __func__
 
 #include <linux/bitmap.h>
+#include <linux/cpu.h>
 #include <linux/debugfs.h>
 #include <linux/export.h>
 #include <linux/io.h>
@@ -20,6 +21,7 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/pm_qos.h>
 #include <linux/property.h>
 #include <linux/semaphore.h>
 #include <linux/slab.h>
@@ -3669,7 +3671,27 @@ static int ti_sci_prepare_system_suspend(struct ti_sci_info *info)
 static int __maybe_unused ti_sci_suspend(struct device *dev)
 {
 	struct ti_sci_info *info = dev_get_drvdata(dev);
-	int ret;
+	struct device *cpu_dev, *cpu_dev_max = NULL;
+	s32 val, cpu_lat = 0;
+	int i, ret;
+
+	if (info->fw_caps & MSG_FLAG_CAPS_LPM_DM_MANAGED) {
+		for_each_possible_cpu(i) {
+			cpu_dev = get_cpu_device(i);
+			val = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_RESUME_LATENCY);
+			if (val != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT) {
+				cpu_lat = max(cpu_lat, val);
+				cpu_dev_max = cpu_dev;
+			}
+		}
+		if (cpu_dev_max) {
+			dev_dbg(cpu_dev_max, "%s: sending max CPU latency=%u\n", __func__, cpu_lat);
+			ret = ti_sci_cmd_set_latency_constraint(&info->handle,
+								cpu_lat, TISCI_MSG_CONSTRAINT_SET);
+			if (ret)
+				return ret;
+		}
+	}
 
 	ret = ti_sci_prepare_system_suspend(info);
 	if (ret)
-- 
2.45.2
Re: [PATCH v11 4/4] firmware: ti_sci: add CPU latency constraint management
Posted by Nathan Chancellor 1 year, 3 months ago 
Hi Markus,

On Thu, Aug 29, 2024 at 10:16:05PM +0200, Markus Schneider-Pargmann wrote:
> From: Kevin Hilman <khilman@baylibre.com>
> 
> During system-wide suspend, check if any of the CPUs have PM QoS
> resume latency constraints set.  If so, set TI SCI constraint.
> 
> TI SCI has a single system-wide latency constraint, so use the max of
> any of the CPU latencies as the system-wide value.
> 
> Note: DM firmware clears all constraints at resume time, so
> constraints need to be checked/updated/sent at each system suspend.
> 
> Co-developed-by: Vibhore Vardhan <vibhore@ti.com>
> Signed-off-by: Vibhore Vardhan <vibhore@ti.com>
> Reviewed-by: Dhruva Gole <d-gole@ti.com>
> Signed-off-by: Dhruva Gole <d-gole@ti.com>
> Signed-off-by: Kevin Hilman <khilman@baylibre.com>
> Tested-by: Dhruva Gole <d-gole@ti.com>
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> ---
>  drivers/firmware/ti_sci.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
> index 8482b7077eef..d5d64e5ffbd7 100644
> --- a/drivers/firmware/ti_sci.c
> +++ b/drivers/firmware/ti_sci.c
> @@ -10,6 +10,7 @@
>  #define pr_fmt(fmt) "%s: " fmt, __func__
>  
>  #include <linux/bitmap.h>
> +#include <linux/cpu.h>
>  #include <linux/debugfs.h>
>  #include <linux/export.h>
>  #include <linux/io.h>
> @@ -20,6 +21,7 @@
>  #include <linux/of.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_qos.h>
>  #include <linux/property.h>
>  #include <linux/semaphore.h>
>  #include <linux/slab.h>
> @@ -3669,7 +3671,27 @@ static int ti_sci_prepare_system_suspend(struct ti_sci_info *info)
>  static int __maybe_unused ti_sci_suspend(struct device *dev)
>  {
>  	struct ti_sci_info *info = dev_get_drvdata(dev);
> -	int ret;
> +	struct device *cpu_dev, *cpu_dev_max = NULL;
> +	s32 val, cpu_lat = 0;
> +	int i, ret;
> +
> +	if (info->fw_caps & MSG_FLAG_CAPS_LPM_DM_MANAGED) {
> +		for_each_possible_cpu(i) {
> +			cpu_dev = get_cpu_device(i);
> +			val = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_RESUME_LATENCY);

This change is now in -next as commit 458d22d2e064 ("firmware: ti_sci:
add CPU latency constraint management"), where it breaks the build
when this driver is built as a module because dev_pm_qos_read_value() is
not exported to modules:

  ERROR: modpost: "dev_pm_qos_read_value" [drivers/firmware/ti_sci.ko] undefined!

Obviously exporting it would fix the build but sometimes that is
controversial, hence just the report.

> +			if (val != PM_QOS_RESUME_LATENCY_NO_CONSTRAINT) {
> +				cpu_lat = max(cpu_lat, val);
> +				cpu_dev_max = cpu_dev;
> +			}
> +		}
> +		if (cpu_dev_max) {
> +			dev_dbg(cpu_dev_max, "%s: sending max CPU latency=%u\n", __func__, cpu_lat);
> +			ret = ti_sci_cmd_set_latency_constraint(&info->handle,
> +								cpu_lat, TISCI_MSG_CONSTRAINT_SET);
> +			if (ret)
> +				return ret;
> +		}
> +	}
>  
>  	ret = ti_sci_prepare_system_suspend(info);
>  	if (ret)
> -- 
> 2.45.2
>
Re: [PATCH v11 4/4] firmware: ti_sci: add CPU latency constraint management
Posted by Nishanth Menon 1 year, 3 months ago 
On 17:54-20240902, Nathan Chancellor wrote:
[...]

> > @@ -3669,7 +3671,27 @@ static int ti_sci_prepare_system_suspend(struct ti_sci_info *info)
> >  static int __maybe_unused ti_sci_suspend(struct device *dev)
> >  {
> >  	struct ti_sci_info *info = dev_get_drvdata(dev);
> > -	int ret;
> > +	struct device *cpu_dev, *cpu_dev_max = NULL;
> > +	s32 val, cpu_lat = 0;
> > +	int i, ret;
> > +
> > +	if (info->fw_caps & MSG_FLAG_CAPS_LPM_DM_MANAGED) {
> > +		for_each_possible_cpu(i) {
> > +			cpu_dev = get_cpu_device(i);
> > +			val = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_RESUME_LATENCY);
> 
> This change is now in -next as commit 458d22d2e064 ("firmware: ti_sci:
> add CPU latency constraint management"), where it breaks the build
> when this driver is built as a module because dev_pm_qos_read_value() is
> not exported to modules:
> 
>   ERROR: modpost: "dev_pm_qos_read_value" [drivers/firmware/ti_sci.ko] undefined!
> 
> Obviously exporting it would fix the build but sometimes that is
> controversial, hence just the report.

Thank you for the report. I will drop the series from my queue for now.
That should give us some time to sort things out properly for the next
window.

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D
Re: [PATCH v11 4/4] firmware: ti_sci: add CPU latency constraint management
Posted by Markus Schneider-Pargmann 1 year, 3 months ago 
Hi,

On Tue, Sep 03, 2024 at 07:45:40AM GMT, Nishanth Menon wrote:
> On 17:54-20240902, Nathan Chancellor wrote:
> [...]
> 
> > > @@ -3669,7 +3671,27 @@ static int ti_sci_prepare_system_suspend(struct ti_sci_info *info)
> > >  static int __maybe_unused ti_sci_suspend(struct device *dev)
> > >  {
> > >  	struct ti_sci_info *info = dev_get_drvdata(dev);
> > > -	int ret;
> > > +	struct device *cpu_dev, *cpu_dev_max = NULL;
> > > +	s32 val, cpu_lat = 0;
> > > +	int i, ret;
> > > +
> > > +	if (info->fw_caps & MSG_FLAG_CAPS_LPM_DM_MANAGED) {
> > > +		for_each_possible_cpu(i) {
> > > +			cpu_dev = get_cpu_device(i);
> > > +			val = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_RESUME_LATENCY);
> > 
> > This change is now in -next as commit 458d22d2e064 ("firmware: ti_sci:
> > add CPU latency constraint management"), where it breaks the build
> > when this driver is built as a module because dev_pm_qos_read_value() is
> > not exported to modules:
> > 
> >   ERROR: modpost: "dev_pm_qos_read_value" [drivers/firmware/ti_sci.ko] undefined!
> > 
> > Obviously exporting it would fix the build but sometimes that is
> > controversial, hence just the report.
> 
> Thank you for the report. I will drop the series from my queue for now.
> That should give us some time to sort things out properly for the next
> window.

Thanks as well for reporting. I looked into this issue and it looks like
many of the dev_pm_qos_* functions are already exported.
Documentation/power/pm_qos_interface.rst also already lists the function
for kernel-internal use along with many others. So I think adding the
export is the right way and I prepared a patch for that.

Also from what I saw and tested, I was only able to reproduce this issue
with ARCH_KEYSTONE when the TI_SCI_PROTOCOL is selected as module.
multi_v7_defconfig and keystone_defconfig both select it as built-in as
well as ARCH_K3. For all other architectures, TI_SCI_PROTOCOL can not be
selected as it depends on TI_MESSAGE_MANAGER which depends on KEYSTONE
or K3.

Best
Markus

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