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

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

[Tommaso Merciai]

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
 - 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);
-- 
2.54.0

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

[Sakari Ailus]

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()?

>  - 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

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

[Tommaso Merciai]

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