Re: [PATCH] memory: tegra: Wire up system sleep PM ops

[Ashish Mhetre <amhetre@nvidia.com>]

On 4/29/2026 3:23 PM, Jon Hunter wrote:
>
> On 29/04/2026 07:11, 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.
>>
>> 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.
>
> Technically, this appears to be two fixes ...
>
> 1. Register the PM ops so that the existing SoC specific resume is
>    called.
> 2. Reprogram the MC interrupt masks for all SoCs on resume.
>
> So ideally this should be split. The first part appears to be a fix 
> for fe3b082a6eb8 ("memory: tegra: Add SID override programming for MC 
> clients"). Although the 2nd part is a fix too, it is only applicable 
> after 9f2614510960 ("memory: tegra: Prepare for supporting multiple 
> intmask registers") so may be a fixes tag is not appropriate here.
>
>

Sure Jon, I'll split the patch in two and resend.

>> Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
>> ---
>>   drivers/memory/tegra/mc.c | 46 +++++++++++++++++++++++++++++++++------
>>   1 file changed, 39 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
>> index d620660da331..cddcefdd16c5 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>
>> @@ -910,6 +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;
>> @@ -970,13 +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) {
>> @@ -1010,10 +1018,34 @@ 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);
>> +    int err;
>> +
>> +    if (mc->soc->ops && mc->soc->ops->resume) {
>> +        err = mc->soc->ops->resume(mc);
>> +        if (err)
>> +            return err;
>> +    }
>> +
>> +    tegra_mc_setup_intmask(mc);
>> +
>> +    return 0;
>> +}
>> +
>> +/*
>> + * No suspend callback is needed because the resume path 
>> reinitializes all
>> + * necessary MC register state (SID overrides, interrupt masks) from 
>> static
>> + * SoC data tables rather than from saved runtime state.
>> + */
>> +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,
>>       },
>
> Otherwise, the change looks fine.
>
> Jon