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

[Lad, Prabhakar]

Hi Jacopo,

Thank you for the patch.

On Fri, Mar 27, 2026 at 5:27 PM Jacopo Mondi
<jacopo.mondi@xxxxxxxxxxxxxxxx> 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>
> ---
>  .../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
> + *
stray change.

>   * @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;
> -
Maybe we can move cru->active_slot assignment here and keep
cru->sequence assignment as is. With that fixed,

Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Cheers,
Prabhakar

>         ret = rzg2l_cru_set_stream(cru, 1);
>         if (ret) {
>                 return_unused_buffers(cru, VB2_BUF_STATE_QUEUED);
>
> --
> 2.53.0
>
>