From: Karunika Choo Date: Thu, 7 Aug 2025 16:26:31 +0000 (+0100) Subject: drm/panthor: Serialize GPU cache flush operations X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=e322a4844811b54477b7072eb40dc9e402a1725d;p=users%2Fhch%2Fmisc.git drm/panthor: Serialize GPU cache flush operations 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 --- diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c index 5e2c3173ae27..db69449a5be0 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; }; #define GPU_INTERRUPTS_MASK \ @@ -110,6 +113,7 @@ 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; dma_set_max_seg_size(ptdev->base.dev, UINT_MAX); @@ -258,6 +262,9 @@ 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)) {