Re: [PATCH 3/3] drm/nouveau/tegra: Keep the fuse clock enabled while the GPU is powered

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] nouveau: tegra: clk_fuse leak on power_down failure
--

commit 4446c1485fff0b05a5e79c1e4d70e14c4beda300
Author: Sasha Levin <sashal@kernel.org>

    drm/nouveau/tegra: Keep the fuse clock enabled while the GPU is powered

This commit modifies nouveau's Tegra power management sequence to keep the
fuse clock enabled while the GPU is powered. This resolves an issue where
the GM20B GPU would fail to initialize on some boots.

> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c b/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
> index 3c8d0878891ad..31f8eaa9d6509 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c

[ ... ]

> @@ -95,6 +100,8 @@ nvkm_device_tegra_power_down(struct nvkm_device_tegra *tdev)
>  			return ret;
>  	}
>  
> +	clk_disable_unprepare(tdev->clk_fuse);
> +
>  	return 0;
>  }

[Severity: Medium]
Does this code leak the clk_fuse enable and prepare counts if
regulator_disable() fails?

If regulator_disable() fails and returns an error, the function immediately
returns early. Because the new clk_disable_unprepare() call is positioned
at the very end of this function, it is skipped entirely on this error path.

Since callers like nvkm_device_tegra_dtor() ignore the return value of
nvkm_device_tegra_power_down() and proceed to free the device structure,
would this result in a permanent resource leak where the clk_fuse's prepare
and enable counts are never decremented?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261013145210.103565-1-sashal@kernel.org?part=3