Re: [PATCH 10/14] media: rzg2l-cru: Manually track active slot number

[Dan Scally]

Hi Jacopo, thanks for the patch

On 27/03/2026 17:10, Jacopo Mondi wrote:
> From: Jacopo Mondi <jacopo.mondi+renesas@xxxxxxxxxxxxxxxx>
>
> The CRU cycles over the hardware slots where the destination address for
> the next frame has to be programmed.
>
> The RZ/G2L version of the IP has a register that tells which is the
> last used slot by the hardware but, unfortunately, such register is not
> available on RZ/G3E and RZ/V2H(P).
>
> The driver currently compares the value of the AMnMADRSL/H register
> which report "the memory address which the current video data was
> written to" and compares it with the address programmed in the slots.
>
> This heuristic requires a bit of book keeping and proper locking. As the
> driver handles the FrameEnd interrupt, it's way easier to keep track
> of the slot that has been used by ourselves with a driver variable.
>
> Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@xxxxxxxxxxxxxxxx>
> ---

Reviewed-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>

>   .../media/platform/renesas/rzg2l-cru/rzg2l-cru.h   |  7 +++--
>   .../media/platform/renesas/rzg2l-cru/rzg2l-video.c | 35 ++++------------------
>   2 files changed, 10 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
> index b46696a0012b..bc66b0c8c15e 100644
> --- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
> +++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-cru.h
> @@ -108,6 +108,7 @@ struct rzg2l_cru_info {
>    * @vdev:		V4L2 video device associated with CRU
>    * @v4l2_dev:		V4L2 device
>    * @num_buf:		Holds the current number of buffers enabled
> + *
>    * @svc_channel:	SVC0/1/2/3 to use for RZ/G3E
>    * @notifier:		V4L2 asynchronous subdevs notifier
>    *
> @@ -117,9 +118,10 @@ 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
> + * @hw_lock:		protects the @active_slot counter, hardware programming
> + *			of slot addresses and the @buf_addr[] list
>    * @buf_addr:		Memory addresses where current video data is written
> + * @active_slot:	The slot in use
>    *
>    * @lock:		protects @queue
>    * @queue:		vb2 buffers queue
> @@ -160,6 +162,7 @@ struct rzg2l_cru_dev {
>   
>   	spinlock_t hw_lock;
>   	dma_addr_t buf_addr[RZG2L_CRU_HW_BUFFER_DEFAULT];
> +	unsigned int active_slot;
>   
>   	struct mutex lock;
>   	struct vb2_queue queue;
> diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> index 9406a089ec9f..17e0153052e1 100644
> --- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> +++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> @@ -637,31 +637,6 @@ irqreturn_t rzg2l_cru_irq(int irq, void *data)
>   	return IRQ_RETVAL(handled);
>   }
>   
> -static int rzg3e_cru_get_current_slot(struct rzg2l_cru_dev *cru)
> -{
> -	u64 amnmadrs;
> -	int slot;
> -
> -	/*
> -	 * When AMnMADRSL is read, AMnMADRSH of the higher-order
> -	 * address also latches the address.
> -	 *
> -	 * AMnMADRSH must be read after AMnMADRSL has been read.
> -	 */
> -	amnmadrs = rzg2l_cru_read(cru, AMnMADRSL);
> -	amnmadrs |= (u64)rzg2l_cru_read(cru, AMnMADRSH) << 32;
> -
> -	/* Ensure amnmadrs is within this buffer range */
> -	for (slot = 0; slot < cru->num_buf; slot++) {
> -		if (amnmadrs >= cru->buf_addr[slot] &&
> -		    amnmadrs < cru->buf_addr[slot] + cru->format.sizeimage)
> -			return slot;
> -	}
> -
> -	dev_err(cru->dev, "Invalid MB address 0x%llx (out of range)\n", amnmadrs);
> -	return -EINVAL;
> -}
> -
>   irqreturn_t rzg3e_cru_irq(int irq, void *data)
>   {
>   	struct rzg2l_cru_dev *cru = data;
> @@ -693,9 +668,8 @@ irqreturn_t rzg3e_cru_irq(int irq, void *data)
>   		return IRQ_HANDLED;
>   	}
>   
> -	slot = rzg3e_cru_get_current_slot(cru);
> -	if (slot < 0)
> -		return IRQ_HANDLED;
> +	slot = cru->active_slot;
> +	cru->active_slot = (cru->active_slot + 1) % cru->num_buf;
>   
>   	dev_dbg(cru->dev, "Current written slot: %d\n", slot);
>   	cru->buf_addr[slot] = 0;
> @@ -762,6 +736,9 @@ static int rzg2l_cru_start_streaming_vq(struct vb2_queue *vq, unsigned int count
>   		goto assert_aresetn;
>   	}
>   
> +	cru->active_slot = 0;
> +	cru->sequence = 0;
> +
>   	/* Allocate scratch buffer */
>   	cru->scratch = dma_alloc_coherent(cru->dev, cru->format.sizeimage,
>   					  &cru->scratch_phys, GFP_KERNEL);
> @@ -772,8 +749,6 @@ static int rzg2l_cru_start_streaming_vq(struct vb2_queue *vq, unsigned int count
>   		goto assert_presetn;
>   	}
>   
> -	cru->sequence = 0;
> -
>   	ret = rzg2l_cru_set_stream(cru, 1);
>   	if (ret) {
>   		return_unused_buffers(cru, VB2_BUF_STATE_QUEUED);