media: rz2gl-cru: Introduce a spinlock for hw operations

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 <jacopo.mondi+renesas@ideasonboard.com>
Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
index be4a9a4953d10876375dc8b5dab34e97332fcdb6..12d574182eb85900c2d8ec95d0ee11ce6a0bff4d 100644 (file)
--- 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 c49131587679a897d248e121a02d304fa732c62b..b6616d54f8a333dbc81cb7110a61e2539e0b8c89 100644 (file)
--- 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;