On Wed Feb 11 09:17:23 2026 +0100, Jacopo Mondi wrote:
> The CRU driver uses a single spinlock to protect the buffers queue and
> the hardware operations.
>
> This single spinlock is held for the whole duration of the interrupt
> handler, causing all other driver's operations to freeze.
>
> Under heavy system stress conditions with userspace not providing
> buffers fast enough, this causes loss of frames.
>
> Prepare to re-work the driver locking by introducing (but not using yet)
> a new spinlock to protect the hardware registers programming.
>
> Signed-off-by: Jacopo Mondi <[email protected]>
> Reviewed-by: Tommaso Merciai <[email protected]>
> Reviewed-by: Daniel Scally <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h | 10 +++++++---
drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c | 1 +
2 files changed, 8 insertions(+), 3 deletions(-)
---
diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
index be4a9a4953d1..12d574182eb8 100644
--- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
+++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
@@ -111,7 +111,6 @@ struct rzg2l_cru_info {
* @v4l2_dev: V4L2 device
* @num_buf: Holds the current number of buffers enabled
* @svc_channel: SVC0/1/2/3 to use for RZ/G3E
- * @buf_addr: Memory addresses where current video data is written.
* @notifier: V4L2 asynchronous subdevs notifier
*
* @ip: Image processing subdev info
@@ -120,6 +119,10 @@ struct rzg2l_cru_info {
* @mdev_lock: protects the count, notifier and csi members
* @pad: media pad for the video device entity
*
+ * @hw_lock: protects the slot counter, hardware programming of
+ * slot addresses and the @buf_addr[] list
+ * @buf_addr: Memory addresses where current video data is written
+ *
* @lock: protects @queue
* @queue: vb2 buffers queue
* @scratch: cpu address for scratch buffer
@@ -149,8 +152,6 @@ struct rzg2l_cru_dev {
u8 num_buf;
u8 svc_channel;
- dma_addr_t buf_addr[RZG2L_CRU_HW_BUFFER_DEFAULT];
-
struct v4l2_async_notifier notifier;
struct rzg2l_cru_ip ip;
@@ -159,6 +160,9 @@ struct rzg2l_cru_dev {
struct mutex mdev_lock;
struct media_pad pad;
+ spinlock_t hw_lock;
+ dma_addr_t buf_addr[RZG2L_CRU_HW_BUFFER_DEFAULT];
+
struct mutex lock;
struct vb2_queue queue;
void *scratch;
diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
index c49131587679..b6616d54f8a3 100644
--- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
+++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
@@ -843,6 +843,7 @@ int rzg2l_cru_dma_register(struct rzg2l_cru_dev *cru)
mutex_init(&cru->lock);
INIT_LIST_HEAD(&cru->buf_list);
+ spin_lock_init(&cru->hw_lock);
spin_lock_init(&cru->qlock);
cru->state = RZG2L_CRU_DMA_STOPPED;
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