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@xxxxxxxxxx>
> > ---
> >   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