Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] panfrost: potential hw bug trigger due to reversed perfcnt disable sequence --
commit 955ad49004b82d4c7b4dae93b28817ea9431d397 Author: Adrián Larumbe <[email protected]> drm/panfrost: Move perfcnt GPU disable sequence into a helper This commit introduces a helper function panfrost_perfcnt_hw_disable to handle the GPU performance counter disable sequence. It updates the existing disable and init/fini paths to use this new helper to avoid code repetition. > diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c > b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c > index 7020c0192e189..f71534e741b65 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c > +++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c > @@ -35,6 +35,16 @@ struct panfrost_perfcnt { > struct completion dump_comp; > }; > > +static void panfrost_perfcnt_hw_disable(struct panfrost_device *pfdev) > +{ > + gpu_write(pfdev, GPU_PERFCNT_CFG, > + GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_OFF)); > + gpu_write(pfdev, GPU_PRFCNT_JM_EN, 0x0); > + gpu_write(pfdev, GPU_PRFCNT_SHADER_EN, 0x0); > + gpu_write(pfdev, GPU_PRFCNT_MMU_L2_EN, 0x0); > + gpu_write(pfdev, GPU_PRFCNT_TILER_EN, 0); > +} [Severity: Medium] Could this sequence reversal cause a hardware lockup or undefined behavior? The new panfrost_perfcnt_hw_disable() helper reverses the previous order by setting GPU_PERFCNT_CFG to OFF while the enable registers are still enabled. Modifying GPU_PERFCNT_CFG while TILER_EN is actively enabled during the teardown path might risk triggering hardware malfunctions similar to the PRLAM-8186 issue, which requires TILER_EN to be 0 before modifying GPU_PERFCNT_CFG to enable counters. Does this disable sequence need to preserve the original ordering seen in panfrost_perfcnt_disable_locked()? [ ... ] > @@ -193,12 +203,7 @@ static int panfrost_perfcnt_disable_locked(struct > panfrost_device *pfdev, > if (user != perfcnt->user) > return -EINVAL; > > - gpu_write(pfdev, GPU_PRFCNT_JM_EN, 0x0); > - gpu_write(pfdev, GPU_PRFCNT_SHADER_EN, 0x0); > - gpu_write(pfdev, GPU_PRFCNT_MMU_L2_EN, 0x0); > - gpu_write(pfdev, GPU_PRFCNT_TILER_EN, 0); > - gpu_write(pfdev, GPU_PERFCNT_CFG, > - GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_OFF)); > + panfrost_perfcnt_hw_disable(pfdev); > > perfcnt->user = NULL; > drm_gem_vunmap(&perfcnt->mapping->obj->base.base, &map); -- Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=11
