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drm/panfrost: Skip cache flush/invalidate when enabling perfcnt

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The GPU cache flush/invalidate operation is unnecessary. In the usual case,
before a perfcnt dump is requested, there will be no stale lines in GPU
caches for the sample BO's physmem pages, since their memory had not
recently been addressed by the GPU.

However, in the off-chance that the sample BO reuses memory that the GPU
had recently addressed and for which it contains stale lines in its caches,
there already was a FLUSH_PT command being issued as part of the buffer GPU
mapping procedure, so by the time panfrost_gem_open() comes back at perfcnt
session enable, stale GPU cache lines should've already been evicted.

In either case, forcing a GPU cache clean when enabling a new session makes
no difference, and removing it simplifies handling of the error path.

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patch.msgid.link/20261012-claude-fixes-v15-12-bc0a6c498553@collabora.com
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
This commit is contained in:
Adrián Larumbe 2026-10-12 15:48:04 +01:00
parent a2858e0f33
commit 711a34a56d
1 changed files with 2 additions and 13 deletions
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15
drivers/gpu/drm/panfrost/panfrost_perfcnt.c
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@ -124,21 +124,10 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
panfrost_gem_internal_set_label(&bo->base, "Perfcnt sample buffer");
/*
* Invalidate the cache and clear the counters to start from a fresh
* state.
* Clear the counters to start from a fresh state.
*/
reinit_completion(&pfdev->perfcnt->dump_comp);
gpu_write(pfdev, GPU_INT_CLEAR,
GPU_IRQ_CLEAN_CACHES_COMPLETED |
GPU_IRQ_PERFCNT_SAMPLE_COMPLETED);
gpu_write(pfdev, GPU_INT_CLEAR, GPU_IRQ_PERFCNT_SAMPLE_COMPLETED);
gpu_write(pfdev, GPU_CMD, GPU_CMD_PERFCNT_CLEAR);
gpu_write(pfdev, GPU_CMD, GPU_CMD_CLEAN_INV_CACHES);
ret = wait_for_completion_timeout(&pfdev->perfcnt->dump_comp,
msecs_to_jiffies(1000));
if (!ret) {
ret = -ETIMEDOUT;
goto err_vunmap;
}
ret = panfrost_mmu_as_get(pfdev, perfcnt->mapping->mmu);
if (ret < 0)