Re: [PATCH 2/2] media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement

[Tommaso Merciai]

Hi Laurent,
Thanks for your review.

On Wed, Jun 24, 2026 at 10:53:34PM +0300, Laurent Pinchart wrote:
> On Wed, Jun 24, 2026 at 12:41:31PM +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()")
> 
> s/commit/Commit/

thanks.

> 
> > replaced the open-coded aligned calculation with v4l2_fill_pixfmt(),
> > which sets no alignment, reintroducing the issue.
> 
> I wonder how I missed that. Sorry.
> 
> > 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.
> > 
> > Fixes: ace92ccef0c9 ("media: platform: rzg2l-cru: Use v4l2_fill_pixfmt()")
> > Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
> > ---
> >  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);
> 
> The documentation states that, for RGB888, the stride has to be a
> multiple of 384 (3*128). Shouldn't you take that into account here ?
> 
> Also, for semi-planar YUV 4:2:0, the hardware seems to use a stride
> equal to AMnIS*2, which leaves blank lines after every U/V line. That's
> something userspace doesn't expect.

Correct.

Currently neither RGB888 nor semi-planar YUV 4:2:0 are supported.
I will handle this once the support for those formats will be added
if for you is ok.

Please let me know.
Thanks.

Kind Regards,
Tommaso

> 
> >  
> >  	dev_dbg(cru->dev, "Format %ux%u bpl: %u size: %u\n",
> >  		pix->width, pix->height, pix->bytesperline, pix->sizeimage);
> 
> -- 
> Regards,
> 
> Laurent Pinchart