[PATCH V2 0/2] memory: tegra: Restore MC state on system resume

[PATCH V2 0/2] memory: tegra: Restore MC state on system resume

[Ashish Mhetre]

The tegra-mc platform driver does not register any dev_pm_ops, so the
SoC-specific ->resume() is never invoked (e.g. tegra186_mc_resume) on
system wake. On Tegra186 and later this means MC client Stream-ID
override registers are not reprogrammed.

Register a dev_pm_ops on the tegra-mc driver and route the system
resume callback into mc->soc->ops->resume() so the existing SID
restore path runs again on wake.

The MC interrupt mask registers also lose state across SC7, so
re-apply them on resume. Factor the existing intmask programming
out of tegra_mc_probe() into tegra_mc_setup_intmask() and reuse it
from both probe and resume to avoid duplicating the loop.

No suspend callback is needed as the resume path reprograms all MC
state from the static SoC tables, so there is nothing to save.

Changes in V2:
- Split the original single patch into two - register the PM ops and
  reprogram the MC interrupt masks on resume.

Ashish Mhetre (2):
  memory: tegra: Wire up system sleep PM ops
  memory: tegra: Restore MC interrupt masks on resume

 drivers/memory/tegra/mc.c | 41 ++++++++++++++++++++++++++++++++-------
 1 file changed, 34 insertions(+), 7 deletions(-)

-- 
2.50.1

[PATCH V2 1/2] memory: tegra: Wire up system sleep PM ops

[Ashish Mhetre]

The tegra-mc platform driver does not register any dev_pm_ops, so the
the SoC-specific ->resume() is never invoked (e.g. tegra186_mc_resume)
on system wake. On Tegra186 and later this means MC client Stream-ID
override registers are not reprogrammed.

Register a dev_pm_ops on the tegra-mc driver and route the system
resume callback into mc->soc->ops->resume() so the existing SID
restore path runs again on wake.

No suspend callback is needed as the resume path reprograms all MC
state from the static SoC tables, so there is nothing to save.

Fixes: fe3b082a6eb8 ("memory: tegra: Add SID override programming for MC clients")
Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
---
 drivers/memory/tegra/mc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
index d620660da331..343ac0018eba 100644
--- a/drivers/memory/tegra/mc.c
+++ b/drivers/memory/tegra/mc.c
@@ -13,6 +13,7 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/pm.h>
 #include <linux/slab.h>
 #include <linux/sort.h>
 #include <linux/tegra-icc.h>
@@ -1010,10 +1011,23 @@ static void tegra_mc_sync_state(struct device *dev)
 		icc_sync_state(dev);
 }
 
+static int tegra_mc_resume(struct device *dev)
+{
+	struct tegra_mc *mc = dev_get_drvdata(dev);
+
+	if (mc->soc->ops && mc->soc->ops->resume)
+		return mc->soc->ops->resume(mc);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(tegra_mc_pm_ops, NULL, tegra_mc_resume);
+
 static struct platform_driver tegra_mc_driver = {
 	.driver = {
 		.name = "tegra-mc",
 		.of_match_table = tegra_mc_of_match,
+		.pm = pm_sleep_ptr(&tegra_mc_pm_ops),
 		.suppress_bind_attrs = true,
 		.sync_state = tegra_mc_sync_state,
 	},
-- 
2.50.1

[PATCH V2 2/2] memory: tegra: Restore MC interrupt masks on resume

[Ashish Mhetre]

The MC interrupt mask registers lose their state across SC7. Without
re-applying them on resume, MC interrupts that were enabled at probe
remain masked after wake, so any post-resume MC error goes unreported.

Factor the existing intmask programming out of tegra_mc_probe() into
tegra_mc_setup_intmask() and reuse it from the system resume callback
so the mask state is restored on wake.

Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
---
 drivers/memory/tegra/mc.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
index 343ac0018eba..ea7b489d666b 100644
--- a/drivers/memory/tegra/mc.c
+++ b/drivers/memory/tegra/mc.c
@@ -911,6 +911,19 @@ static void tegra_mc_num_channel_enabled(struct tegra_mc *mc)
 	}
 }
 
+static void tegra_mc_setup_intmask(struct tegra_mc *mc)
+{
+	unsigned int i;
+
+	for (i = 0; i < mc->soc->num_intmasks; i++) {
+		if (mc->soc->num_channels)
+			mc_ch_writel(mc, MC_BROADCAST_CHANNEL, mc->soc->intmasks[i].mask,
+				     mc->soc->intmasks[i].reg);
+		else
+			mc_writel(mc, mc->soc->intmasks[i].mask, mc->soc->intmasks[i].reg);
+	}
+}
+
 static int tegra_mc_probe(struct platform_device *pdev)
 {
 	struct tegra_mc *mc;
@@ -971,13 +984,7 @@ static int tegra_mc_probe(struct platform_device *pdev)
 			}
 		}
 
-		for (i = 0; i < mc->soc->num_intmasks; i++) {
-			if (mc->soc->num_channels)
-				mc_ch_writel(mc, MC_BROADCAST_CHANNEL, mc->soc->intmasks[i].mask,
-					     mc->soc->intmasks[i].reg);
-			else
-				mc_writel(mc, mc->soc->intmasks[i].mask, mc->soc->intmasks[i].reg);
-		}
+		tegra_mc_setup_intmask(mc);
 	}
 
 	if (mc->soc->reset_ops) {
@@ -1014,9 +1021,15 @@ static void tegra_mc_sync_state(struct device *dev)
 static int tegra_mc_resume(struct device *dev)
 {
 	struct tegra_mc *mc = dev_get_drvdata(dev);
+	int err;
+
+	if (mc->soc->ops && mc->soc->ops->resume) {
+		err = mc->soc->ops->resume(mc);
+		if (err)
+			return err;
+	}
 
-	if (mc->soc->ops && mc->soc->ops->resume)
-		return mc->soc->ops->resume(mc);
+	tegra_mc_setup_intmask(mc);
 
 	return 0;
 }
-- 
2.50.1

Re: [PATCH V2 1/2] memory: tegra: Wire up system sleep PM ops

[Jon Hunter]

On 30/04/2026 08:09, Ashish Mhetre wrote:
> The tegra-mc platform driver does not register any dev_pm_ops, so the
> the SoC-specific ->resume() is never invoked (e.g. tegra186_mc_resume)
> on system wake. On Tegra186 and later this means MC client Stream-ID
> override registers are not reprogrammed.
> 
> Register a dev_pm_ops on the tegra-mc driver and route the system
> resume callback into mc->soc->ops->resume() so the existing SID
> restore path runs again on wake.
> 
> No suspend callback is needed as the resume path reprograms all MC
> state from the static SoC tables, so there is nothing to save.
> 
> Fixes: fe3b082a6eb8 ("memory: tegra: Add SID override programming for MC clients")
> Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
> ---
>   drivers/memory/tegra/mc.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
> index d620660da331..343ac0018eba 100644
> --- a/drivers/memory/tegra/mc.c
> +++ b/drivers/memory/tegra/mc.c
> @@ -13,6 +13,7 @@
>   #include <linux/of.h>
>   #include <linux/of_platform.h>
>   #include <linux/platform_device.h>
> +#include <linux/pm.h>
>   #include <linux/slab.h>
>   #include <linux/sort.h>
>   #include <linux/tegra-icc.h>
> @@ -1010,10 +1011,23 @@ static void tegra_mc_sync_state(struct device *dev)
>   		icc_sync_state(dev);
>   }
>   
> +static int tegra_mc_resume(struct device *dev)
> +{
> +	struct tegra_mc *mc = dev_get_drvdata(dev);
> +
> +	if (mc->soc->ops && mc->soc->ops->resume)
> +		return mc->soc->ops->resume(mc);

I noticed that the tegra186_mc_resume never fails and always returns 0. 
Given that this is the only resume handler, it seem that we should 
change this to a void return type and then we can avoid the extra return 
here. This also simplifies the next patch. So may be we should add one 
more patch to change the return type for this resume callback.

If we ever need to return a error code in the future we can add back, 
but if we don't need it now, then I don't see why we should keep this.

Jon

-- 
nvpublic

Re: [PATCH V2 1/2] memory: tegra: Wire up system sleep PM ops

[Ashish Mhetre]

On 4/30/2026 2:09 PM, Jon Hunter wrote:
>
>
> On 30/04/2026 08:09, Ashish Mhetre wrote:
>> The tegra-mc platform driver does not register any dev_pm_ops, so the
>> the SoC-specific ->resume() is never invoked (e.g. tegra186_mc_resume)
>> on system wake. On Tegra186 and later this means MC client Stream-ID
>> override registers are not reprogrammed.
>>
>> Register a dev_pm_ops on the tegra-mc driver and route the system
>> resume callback into mc->soc->ops->resume() so the existing SID
>> restore path runs again on wake.
>>
>> No suspend callback is needed as the resume path reprograms all MC
>> state from the static SoC tables, so there is nothing to save.
>>
>> Fixes: fe3b082a6eb8 ("memory: tegra: Add SID override programming for 
>> MC clients")
>> Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
>> ---
>>   drivers/memory/tegra/mc.c | 14 ++++++++++++++
>>   1 file changed, 14 insertions(+)
>>
>> diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
>> index d620660da331..343ac0018eba 100644
>> --- a/drivers/memory/tegra/mc.c
>> +++ b/drivers/memory/tegra/mc.c
>> @@ -13,6 +13,7 @@
>>   #include <linux/of.h>
>>   #include <linux/of_platform.h>
>>   #include <linux/platform_device.h>
>> +#include <linux/pm.h>
>>   #include <linux/slab.h>
>>   #include <linux/sort.h>
>>   #include <linux/tegra-icc.h>
>> @@ -1010,10 +1011,23 @@ static void tegra_mc_sync_state(struct device 
>> *dev)
>>           icc_sync_state(dev);
>>   }
>>   +static int tegra_mc_resume(struct device *dev)
>> +{
>> +    struct tegra_mc *mc = dev_get_drvdata(dev);
>> +
>> +    if (mc->soc->ops && mc->soc->ops->resume)
>> +        return mc->soc->ops->resume(mc);
>
> I noticed that the tegra186_mc_resume never fails and always returns 
> 0. Given that this is the only resume handler, it seem that we should 
> change this to a void return type and then we can avoid the extra 
> return here. This also simplifies the next patch. So may be we should 
> add one more patch to change the return type for this resume callback.
>
> If we ever need to return a error code in the future we can add back, 
> but if we don't need it now, then I don't see why we should keep this.
>
> Jon
>

Okay, I'll update the return-type in new patch and send V3.

Thanks,
Ashish Mhetre