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

[Jacopo Mondi]

Hi Tommaso

On Mon, Mar 30, 2026 at 06:25:59PM +0200, Tommaso Merciai wrote:
>
> Hi Jacopo,
> Thanks for your patch,
>
> On Fri, Mar 27, 2026 at 06:10:15PM +0100, 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>
> > ---
> >  .../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
> > + *
>
> Maybe you can drop this.
> Sorry for the nitpick.

Should I ?

The rest of the documentation has blank lines that match the ones in
the struct members declaration. I think I should try to be consistent.

>
> >   * @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);
> >
> > --
> > 2.53.0
> >
>
> Tested-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
>
> Kind Regards,
> Tommaso
>
>