6.17-stable review patch. If anyone has any objections, please let me know.
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From: Karunika Choo karunika.choo@arm.com
[ 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 liviu.dudau@arm.com Co-developed-by: Dennis Tsiang dennis.tsiang@arm.com Signed-off-by: Dennis Tsiang dennis.tsiang@arm.com Signed-off-by: Karunika Choo karunika.choo@arm.com Reviewed-by: Steven Price steven.price@arm.com Signed-off-by: Steven Price steven.price@arm.com Link: https://lore.kernel.org/r/20250807162633.3666310-6-karunika.choo@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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)) {