From a26e36c5eed9a0f80f420836c08693fd7f5d06bb Mon Sep 17 00:00:00 2001 From: Karunika Choo Date: Thu, 7 Aug 2025 17:26:31 +0100 Subject: [PATCH] drm/panthor: Serialize GPU cache flush operations [ Upstream commit e322a4844811b54477b7072eb40dc9e402a1725d ] In certain scenarios, it is possible for multiple cache flushes to be requested before the previous one completes. This patch introduces the cache_flush_lock mutex to serialize these operations and ensure that any requested cache flushes are completed instead of dropped. Reviewed-by: Liviu Dudau Co-developed-by: Dennis Tsiang Signed-off-by: Dennis Tsiang Signed-off-by: Karunika Choo Reviewed-by: Steven Price Signed-off-by: Steven Price Link: https://lore.kernel.org/r/20250807162633.3666310-6-karunika.choo@arm.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/panthor/panthor_gpu.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c index cb7a335e07d7c..030409371037b 100644 --- a/drivers/gpu/drm/panthor/panthor_gpu.c +++ b/drivers/gpu/drm/panthor/panthor_gpu.c @@ -35,6 +35,9 @@ struct panthor_gpu { /** @reqs_acked: GPU request wait queue. */ wait_queue_head_t reqs_acked; + + /** @cache_flush_lock: Lock to serialize cache flushes */ + struct mutex cache_flush_lock; }; /** @@ -204,6 +207,7 @@ int panthor_gpu_init(struct panthor_device *ptdev) spin_lock_init(&gpu->reqs_lock); init_waitqueue_head(&gpu->reqs_acked); + mutex_init(&gpu->cache_flush_lock); ptdev->gpu = gpu; panthor_gpu_init_info(ptdev); @@ -353,6 +357,9 @@ int panthor_gpu_flush_caches(struct panthor_device *ptdev, bool timedout = false; unsigned long flags; + /* Serialize cache flush operations. */ + guard(mutex)(&ptdev->gpu->cache_flush_lock); + spin_lock_irqsave(&ptdev->gpu->reqs_lock, flags); if (!drm_WARN_ON(&ptdev->base, ptdev->gpu->pending_reqs & GPU_IRQ_CLEAN_CACHES_COMPLETED)) { -- 2.47.3