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

[Jacopo Mondi]

On Tue, Mar 31, 2026 at 12:03:22PM +0200, Jacopo Mondi wrote:
> Hi Prabhakar
>
> On Tue, Mar 31, 2026 at 09:30:02AM +0100, Lad, Prabhakar wrote:
> > 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.
> >
>
> As replied to Tommaso, all the other comments have a blank line that
> match the one in the structure's members declarations.
>

BUt you're both right this change might not be strictly related to
this patch. As both of you had the same comment, I'll drop it.

Sorry for the noise.

> > >   * @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>
>
> I can do that
>
> Thanks
>   j
>
> >
> > Cheers,
> > Prabhakar
> >
> > >         ret = rzg2l_cru_set_stream(cru, 1);
> > >         if (ret) {
> > >                 return_unused_buffers(cru, VB2_BUF_STATE_QUEUED);
> > >
> > > --
> > > 2.53.0
> > >
> > >