Subject: Re: [PATCH 05/16] media: v4l2-common: Fix NV15_4L4 format info block height

From: Paul Kocialkowski <[email-masked]>
Date: Tue, 19 May 2026 22:33:59 +0200

Hi Nicolas,

Thanks for the review!

Le Tue 19 May 26, 11:16, Nicolas Dufresne a écrit :
> Le lundi 18 mai 2026 à 12:24 +0200, Paul Kocialkowski a écrit :
> > The NV15_4L4 format is specified as a 4x4 format, not 4x1.
> > In addition the block size should not take subsampling in account,
> > so specify it as 4x4 for both luma and chroma.
> > 
> > Signed-off-by: Paul Kocialkowski <[email-masked]>
> > ---
> >  drivers/media/v4l2-core/v4l2-common.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> > index 554c591e1113..77a0daa92c2b 100644
> > --- a/drivers/media/v4l2-core/v4l2-common.c
> > +++ b/drivers/media/v4l2-core/v4l2-common.c
> > @@ -309,7 +309,7 @@ const struct v4l2_format_info *v4l2_format_info(u32 format)
> >  		/* Tiled YUV formats */
> >  		{ .format = V4L2_PIX_FMT_NV12_4L4, .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 2, .bpp = { 1, 2, 0, 0 }, .bpp_div = { 1, 1, 1, 1 }, .hdiv = 2, .vdiv = 2 },
> >  		{ .format = V4L2_PIX_FMT_NV15_4L4, .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 2, .bpp = { 5, 10, 0, 0 }, .bpp_div = { 4, 4, 1, 1 }, .hdiv = 2, .vdiv = 2,
> > -		  .block_w = { 4, 2, 0, 0 }, .block_h = { 1, 1, 0, 0 }},
> > +		  .block_w = { 4, 4, 0, 0 }, .block_h = { 4, 4, 0, 0 }},
> 
> Only the block_h is broken. The block_w is in "pixels" which for the UV plane is
> component pairs. So both set of tiles have 5bytes stride. But since the second
> set, the UV tiles, are interleaved, they only have 2 pairs of UV per row. So to
> me the correct fix is:
> 
> +		  .block_w = { 4, 2, 0, 0 }, .block_h = { 4, 4, 0, 0 }},
> 
> If its not the case for the camera pipeline, then a new format is needed, since
> this format should perfectly match NV15 + VIVANTE_TILED in the DRM world.

Ah yes I think you're right, I lost sight that these are semi-planar
formats with two components per chroma memory plane.

Good catch, thanks!

All the best,

Paul

> regards,
> Nicolas
> 
> >  		{ .format = V4L2_PIX_FMT_P010_4L4, .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 2, .bpp = { 2, 4, 0, 0 }, .bpp_div = { 1, 1, 1, 1 }, .hdiv = 2, .vdiv = 2 },
> >  
> >  		/* YUV planar formats, non contiguous variant */

-- 
Paul Kocialkowski,

Independent contractor - sys-base - https://www.sys-base.io/
Free software developer - https://www.paulk.fr/

Expert in multimedia, graphics and embedded hardware support with Linux.