[PATCH v9 12/16] drm/panfrost: Skip cache flush/invalidate when enabling perfcnt

["Adrián Larumbe" <adrian.larumbe@collabora.com>]

The GPU cache flush/invalidate operation is unnecessary. First off, the
GPU doesn't read off the perfcnt sample buffer, only writes into it, so
an invalidate doesn't make a difference. Then flushing GPU caches after
each sample has been written is enough for the CPU to see updated values.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_perfcnt.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
index f71534e741b6..ffc77121070e 100644
--- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
+++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
@@ -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)

-- 
2.55.0