Re: [PATCH v5 03/15] media: v4l2-common: Support custom imagesize/bytesperline in fill_pixfmt()

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Boris Brezillon <boris.brezillon@collabora.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Hans Verkuil <hans.verkuil@cisco.com>,
	Sakari Ailus <sakari.ailus@iki.fi>,
	linux-media@vger.kernel.org, Tomasz Figa <tfiga@chromium.org>,
	Nicolas Dufresne <nicolas@ndufresne.ca>,
	kernel@collabora.com,
	Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
	Ezequiel Garcia <ezequiel@collabora.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	linux-rockchip@lists.infradead.org,
	Heiko Stuebner <heiko@sntech.de>,
	Kieran Bingham <kieran.bingham@ideasonboard.com>
Subject: Re: [PATCH v5 03/15] media: v4l2-common: Support custom imagesize/bytesperline in fill_pixfmt()
Date: Fri, 10 May 2019 14:28:47 +0300	[thread overview]
Message-ID: <20190510112847.GA4972@pendragon.ideasonboard.com> (raw)
In-Reply-To: <0c5a648c-27a8-8195-8ad9-8cefb4369837@xs4all.nl>

Hi Hans,

(CC'ing Kieran)

On Fri, May 10, 2019 at 10:57:26AM +0200, Hans Verkuil wrote:
> On 5/3/19 1:47 PM, Boris Brezillon wrote:
> > Users can define custom sizeimage and bytesperline 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.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > ---
> > Hello Hans,
> > 
> > The sizeimage/bytesperline check on !MPLANE formats is still not 100%
> > sure, as custom bytesperline might induce bigger sizeimage than what
> > we calculate.
> > 
> > I tried implementing something smarter taking the per-component plane
> > bpp + hdiv param as we discussed the other day but decided to step
> > back after realizing the per-component plane macro block might also
> > differ at least in theory (not sure that's true in practice) and that
> > has an impact on bytesperline too.
> > 
> > Let me know how you want to handle that case.
> > 
> > Regards,
> > 
> > Boris
> > 
> > Changes in v5:
> > * New patch
> > ---
> >  drivers/media/v4l2-core/v4l2-common.c | 54 +++++++++++++++++++--------
> >  1 file changed, 39 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> > index 3c6f5c115fc5..37bfc984a8b5 100644
> > --- a/drivers/media/v4l2-core/v4l2-common.c
> > +++ b/drivers/media/v4l2-core/v4l2-common.c
> > @@ -563,9 +563,10 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt,
> >  	pixfmt->num_planes = info->mem_planes;
> >  
> >  	if (info->mem_planes == 1) {
> > +		u32 bytesperline, sizeimage = 0;
> > +
> >  		plane = &pixfmt->plane_fmt[0];
> > -		plane->bytesperline = ALIGN(width, v4l2_format_block_width(info, 0)) * info->bpp[0];
> > -		plane->sizeimage = 0;
> > +		bytesperline = ALIGN(width, v4l2_format_block_width(info, 0)) * info->bpp[0];
> >  
> >  		for (i = 0; i < info->comp_planes; i++) {
> >  			unsigned int hdiv = (i == 0) ? 1 : info->hdiv;
> > @@ -576,10 +577,17 @@ 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);
> >  		}
> > +
> > +		/*
> > +		 * The user might have specified custom sizeimage/bytesperline,
> > +		 * only override them if they're not big enough.
> > +		 */
> > +		plane->sizeimage = max(sizeimage, plane->sizeimage);
> > +		plane->bytesperline = max(bytesperline, plane->bytesperline);
> 
> Let's just set bytesperline, ignoring the value the user supplied. There are very
> few drivers that allow the user to set bytesperline anyway, so it's not a big deal
> to drop support for that for now. We can add it back later.
> 
> Just add a comment that a user-defined bytesperline value isn't currently supported.

Kieran recently ran into an issue related to this, when sharing buffers
between a CSI-2 receiver and an ISP. The ISP has alignment constraints
in both the horizontal and vertical directions on the line stride and
total image size. Out software framework currently allocates buffers
from the CSI-2 receiver which doesn't have those constraints, and not
being able to specify sizeimage is thus a problem.

We have worked around this by allocating buffers on the ISP side but
that departed from the normal way of operation, and it may not be a good
idea to carry that forward.

I wonder how we should solve these issues long term. A central memory
allocator is probably the way to go.

> >  	} else {
> >  		for (i = 0; i < info->comp_planes; i++) {
> >  			unsigned int hdiv = (i == 0) ? 1 : info->hdiv;
> > @@ -591,10 +599,20 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt,
> >  			aligned_height = ALIGN(height, v4l2_format_block_height(info, i));
> >  
> >  			plane = &pixfmt->plane_fmt[i];
> > -			plane->bytesperline =
> > -				info->bpp[i] * DIV_ROUND_UP(aligned_width, hdiv);
> > -			plane->sizeimage =
> > -				plane->bytesperline * DIV_ROUND_UP(aligned_height, vdiv);
> > +
> > +			/*
> > +			 * The user might have specified custom
> > +			 * sizeimage/bytesperline, only override them if
> > +			 * they're not big enough.
> > +			 */
> > +			plane->bytesperline = max_t(u32,
> > +						    info->bpp[i] *
> > +						    DIV_ROUND_UP(aligned_width, hdiv),
> > +						    plane->bytesperline);
> > +			plane->sizeimage = max_t(u32,
> > +						 plane->bytesperline *
> > +						 DIV_ROUND_UP(aligned_height, vdiv),
> > +						 plane->sizeimage);
> >  		}
> >  	}
> >  	return 0;
> > @@ -605,6 +623,7 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
> >  		     u32 width, u32 height)
> >  {
> >  	const struct v4l2_format_info *info;
> > +	u32 bytesperline, sizeimage = 0;
> >  	int i;
> >  
> >  	info = v4l2_format_info(pixelformat);
> > @@ -618,8 +637,7 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
> >  	pixfmt->width = width;
> >  	pixfmt->height = height;
> >  	pixfmt->pixelformat = pixelformat;
> > -	pixfmt->bytesperline = ALIGN(width, v4l2_format_block_width(info, 0)) * info->bpp[0];
> > -	pixfmt->sizeimage = 0;
> > +	bytesperline = ALIGN(width, v4l2_format_block_width(info, 0)) * info->bpp[0];
> >  
> >  	for (i = 0; i < info->comp_planes; i++) {
> >  		unsigned int hdiv = (i == 0) ? 1 : info->hdiv;
> > @@ -629,11 +647,17 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
> >  
> >  		aligned_width = ALIGN(width, v4l2_format_block_width(info, i));
> >  		aligned_height = ALIGN(height, v4l2_format_block_height(info, i));
> > -
> > -		pixfmt->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);
> >  	}
> > +
> > +	/*
> > +	 * The user might have specified its own sizeimage/bytesperline values,
> > +	 * only override them if they're not big enough.
> > +	 */
> > +	pixfmt->sizeimage = max(sizeimage, pixfmt->sizeimage);
> > +	pixfmt->bytesperline = max(bytesperline, pixfmt->bytesperline);
> > +
> >  	return 0;
> >  }
> >  EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt);

-- 
Regards,

Laurent Pinchart