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

[Laurent Pinchart]

On Thu, Jun 25, 2026 at 01:01:09PM +0200, Tommaso Merciai wrote:
> 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.

Ah right I should have checked which formats the driver supports. This
can indeed be addressed later.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>

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

-- 
Regards,

Laurent Pinchart