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

[Jon Hunter <jonathanh@nvidia.com>]

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

-- 
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