Re: [PATCH v6 03/16] media: v4l2-common: Support custom imagesize in fill_pixfmt()

[Boris Brezillon <boris.brezillon@collabora.com>]

On Wed, 29 May 2019 09:26:32 -0300
Mauro Carvalho Chehab <mchehab+samsung@kernel.org> wrote:

> Em Wed, 29 May 2019 14:16:33 +0200
> Boris Brezillon <boris.brezillon@collabora.com> escreveu:
> 
> > On Wed, 29 May 2019 08:58:54 -0300
> > Mauro Carvalho Chehab <mchehab+samsung@kernel.org> wrote:
> >   
> > > Em Wed, 29 May 2019 13:43:20 +0200
> > > Hans Verkuil <hverkuil@xs4all.nl> escreveu:
> > >     
> > > > On 5/29/19 1:28 PM, Mauro Carvalho Chehab wrote:      
> > > > > Em Tue, 28 May 2019 14:02:19 -0300
> > > > > Ezequiel Garcia <ezequiel@collabora.com> escreveu:
> > > > >         
> > > > >> From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > >>
> > > > >> Users can define custom sizeimage as long as they're big enough to
> > > > >> store the amount of pixels required for a specific width/height under a
> > > > >> specific format. Avoid overriding those fields in this case.
> > > > >>
> > > > >> We could possibly do the same for bytesperline, but it gets tricky when
> > > > >> dealing with !MPLANE definitions, so this case is omitted for now and        
> > > > >> ->bytesperline is always overwritten with the value calculated in        
> > > > >> fill_pixfmt().
> > > > >>
> > > > >> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > > > >> ---
> > > > >> Changes from v5:
> > > > >> * Overwrite bytesperline with the value calculated in fill_pixfmt()
> > > > >>
> > > > >> Changes from v4:
> > > > >> * New patch
> > > > >>
> > > > >>  drivers/media/v4l2-core/v4l2-common.c | 58 ++++++++++++++++++++-------
> > > > >>  1 file changed, 43 insertions(+), 15 deletions(-)
> > > > >>
> > > > >> diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> > > > >> index b2d1e55d9561..fd286f6e17d7 100644
> > > > >> --- a/drivers/media/v4l2-core/v4l2-common.c
> > > > >> +++ b/drivers/media/v4l2-core/v4l2-common.c
> > > > >> @@ -585,9 +585,9 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt,
> > > > >>  	pixfmt->num_planes = info->mem_planes;
> > > > >>  
> > > > >>  	if (info->mem_planes == 1) {
> > > > >> +		u32 sizeimage = 0;
> > > > >> +
> > > > >>  		plane = &pixfmt->plane_fmt[0];
> > > > >> -		plane->bytesperline = ALIGN(width, v4l2_format_block_width(info, 0)) * info->bpp[0];
> > > > >> -		plane->sizeimage = 0;
> > > > >>  
> > > > >>  		for (i = 0; i < info->comp_planes; i++) {
> > > > >>  			unsigned int hdiv = (i == 0) ? 1 : info->hdiv;
> > > > >> @@ -598,10 +598,21 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt,
> > > > >>  			aligned_width = ALIGN(width, v4l2_format_block_width(info, i));
> > > > >>  			aligned_height = ALIGN(height, v4l2_format_block_height(info, i));
> > > > >>  
> > > > >> -			plane->sizeimage += info->bpp[i] *
> > > > >> -				DIV_ROUND_UP(aligned_width, hdiv) *
> > > > >> -				DIV_ROUND_UP(aligned_height, vdiv);
> > > > >> +			sizeimage += info->bpp[i] *
> > > > >> +				     DIV_ROUND_UP(aligned_width, hdiv) *
> > > > >> +				     DIV_ROUND_UP(aligned_height, vdiv);
> > > > >>  		}
> > > > >> +
> > > > >> +		/* Custom bytesperline value is not supported yet. */
> > > > >> +		plane->bytesperline = ALIGN(width,
> > > > >> +					    v4l2_format_block_width(info, 0)) *
> > > > >> +				      info->bpp[0];
> > > > >> +
> > > > >> +		/*
> > > > >> +		 * The user might have specified a custom sizeimage, only
> > > > >> +		 * override it if it's not big enough.
> > > > >> +		 */
> > > > >> +		plane->sizeimage = max(sizeimage, plane->sizeimage);        
> > > > > 
> > > > > No upper limit? That doesn't sound a good idea to me, specially since some
> > > > > (broken) app might not be memset the format to zero before filling the ioctl
> > > > > structure.
> > > > > 
> > > > > Perhaps we could do something like:
> > > > > 
> > > > > 		sizeimage = min (sizeimage, 2 * plane->sizeimage)
> > > > > 
> > > > > or something similar that would be reasonable.        
> > > > 
> > > > I've no idea what's sane.
> > > > 
> > > > Buffers can be really large. The largest video resolution defined by CTA-861-G
> > > > is 10240x4320, so at 4 bytes per pixel that's 0x0a8c0000. So perhaps we can
> > > > use min(sizeimage, 0x10000000)? Although we should probably use the clamp function
> > > > instead of min/max.      
> > > 
> > > Well, the max is driver-specific. 
> > > 
> > > For example, for a camera with a max resolution of 640x480 with 2 bytes
> > > per pixel as the max format can only be
> > > 
> > > 	max_size = 640*480*2 (plus some alignment value if pertinent)
> > > 
> > > It sounds to me that the best would be to have a callback function
> > > or value filled by the drivers that would support custom sizeimage.
> > > 
> > > The core could actually calculate during init (by asking the driver
> > > to a very big resolution and getting the returned value), but
> > > it sounds better to let the drivers to explicitly calculate it.    
> > 
> > If we want max_sizeimage to be driver specific I can add it as an extra
> > arg to the fill_pixfmt() funcs.  
> 
> Works for me.
> 
> > If that works for you, we'll send a new version of this patch alone
> > (unless you want us to send the whole series again).  
> 
> If the other patches on this series don't depend on this, I can
> apply the PR just skipping this one, applying your patch afterwards.

Unfortunately they do. I was just asking if we could send a new version
of this patch and let you or Hans apply the other ones from this series
on top. If that's too complicated, we'll submit a v7 containing all
patches. BTW, any concerns on other patches in this series before we
send a new version?