Re: [PATCH v2 4/4] media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement

[Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>]

Hi Sakari,
Thanks for your review.

On Tue, Jul 28, 2026 at 04:08:31PM +0300, Sakari Ailus wrote:
> Hi Tommaso,
> 
> On Wed, Jul 01, 2026 at 06:50:01PM +0200, Tommaso Merciai wrote:
> > The RZ/G3E CRU programs the line stride via the AMnIS register, whose
> > IS field encodes the value in units of 128 bytes. If bytesperline is
> > not a multiple of 128, the division truncates and the hardware uses a
> > wrong stride, causing horizontal banding.
> > 
> > Commit ace92ccef0c9 ("media: platform: rzg2l-cru: Use v4l2_fill_pixfmt()")
> > replaced the open-coded aligned calculation with v4l2_fill_pixfmt(),
> > which sets no alignment, reintroducing the issue.
> > 
> > Switch to v4l2_fill_pixfmt_aligned() with RZG2L_CRU_STRIDE_ALIGN when
> > info->has_stride is set. RZ/G2L has no AMnIS register and keeps using
> > v4l2_fill_pixfmt() unchanged.
> > 
> > Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > Cc: stable@vger.kernel.org
> > Fixes: ace92ccef0c9 ("media: platform: rzg2l-cru: Use v4l2_fill_pixfmt()")
> > Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> > ---
> > v1->v2:
> >  - Collected tag
> >  - Add missing Cc stable
> 
> The problem with this is that it requires v4l2_fill_pixfmt_aligned() that's
> not Cc'd to stable. Can this be fixed first without introducing the use of
> v4l2_fill_pixfmt_aligned() (cc'd to stable, i.e. in this patch), followed
> by another one switching to v4l2_fill_pixfmt_aligned()?

Ok.

I will send add to v5 series before [1] a patch that fixes this
without introducing the use of v4l2_fill_pixfmt_aligned() this I think
can be done using:

        v4l2_fill_pixfmt(pix, pix->pixelformat, pix->width, pix->height);

+       if (info->has_stride) {
+               pix->bytesperline = ALIGN(pix->bytesperline, RZG2L_CRU_STRIDE_ALIGN);
+               pix->sizeimage = pix->bytesperline * pix->height;
+       }
+

Then I rework this patch into:

media: rzg2l-cru: Use v4l2_fill_pixfmt_aligned() for stride alignment

That just use the newly added v4l2_fill_pixfmt_aligned() as you suggest.


[1] https://patchwork.kernel.org/project/linux-renesas-soc/patch/20260713080259.21835-5-tommaso.merciai.xr@bp.renesas.com/


Kind Regards,
Tommaso

> 
> >  - Fix s/commit/Commit/ into commit body
> > 
> >  drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> > index 69346a585f9f..478264f26466 100644
> > --- a/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> > +++ b/drivers/media/platform/renesas/rzg2l-cru/rzg2l-video.c
> > @@ -860,7 +860,8 @@ static void rzg2l_cru_format_align(struct rzg2l_cru_dev *cru,
> >  	v4l_bound_align_image(&pix->width, 320, info->max_width, 1,
> >  			      &pix->height, 240, info->max_height, 0, 0);
> >  
> > -	v4l2_fill_pixfmt(pix, pix->pixelformat, pix->width, pix->height);
> > +	v4l2_fill_pixfmt_aligned(pix, pix->pixelformat, pix->width, pix->height,
> > +				 info->has_stride ? RZG2L_CRU_STRIDE_ALIGN : 1);
> >  
> >  	dev_dbg(cru->dev, "Format %ux%u bpl: %u size: %u\n",
> >  		pix->width, pix->height, pix->bytesperline, pix->sizeimage);
> 
> -- 
> Regards,
> 
> Sakari Ailus