Re: [igt-dev] [PATCH v6 03/13] fb: Create common function to convert frame formats

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Sep 06, 2018 at 01:41:29PM +0200, Maxime Ripard wrote:
> On Fri, Aug 31, 2018 at 04:41:10PM +0300, Ville Syrjälä wrote:
> > On Fri, Aug 31, 2018 at 03:12:12PM +0200, Maxime Ripard wrote:
> > > The current code to convert between two buffer formats is quite tied to the
> > > cairo surface infrastructure. Since we'll want to reuse it, make that
> > > function more generic by introducing a common structure that passes all the
> > > arguments and a common function that will call the right functions we
> > > needed.
> > > 
> > > Reviewed-by: Eric Anholt <eric@anholt.net>
> > > Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
> > > ---
> > >  lib/igt_fb.c | 243 ++++++++++++++++++++++++++++++++--------------------
> > >  1 file changed, 153 insertions(+), 90 deletions(-)
> > > 
> > > diff --git a/lib/igt_fb.c b/lib/igt_fb.c
> > > index 4061fedec0c1..1914233786a5 100644
> > > --- a/lib/igt_fb.c
> > > +++ b/lib/igt_fb.c
> > > @@ -1384,6 +1384,24 @@ struct fb_convert_blit_upload {
> > >  	struct fb_blit_linear linear;
> > >  };
> > >  
> > > +struct fb_convert_buf {
> > > +	void			*ptr;
> > > +	unsigned int		stride;
> > > +	unsigned int		size;
> > > +	uint32_t		fmt;
> > > +	enum igt_color_encoding	color_encoding;
> > > +	enum igt_color_range	color_range;
> > > +	uint32_t		offsets[4];
> > > +};
> > 
> > I wonder if we can just use igt_fb for that instead of duplicating most
> > of it?
> 
> After looking into it again, now I remember why I didn't do what you
> suggested. In the case where you are in the YUYV path, with a "shadow"
> buffer being used to perform the cairo operations on top of an YUV
> buffer, you end up with conversions in create_cairo_surface__convert
> and destroy_cairo_surface__convert, getting a fb_convert_blit_upload
> structure as an argument.
> 
> That structure however is used to convert one buffer to the shadow
> buffer, or the other way around at destroy time. However, a single
> igt_fb is allocated for that structure, which makes it impossible to
> assign the second fb in that particular case. All the informations
> needed to perform the conversion are stored in multiple structures
> (fb_convert_blit_upload.linear, fb_convert_blit_upload.blit, and the
> actual igt_fb instance) that we need to aggregate to find the correct
> conversion parameters.

The patch series I mentioned before [1] changes fb_blit_linear to inherit
from igt_fb. So presumably that should help?

[1] https://patchwork.freedesktop.org/series/46876/

-- 
Ville Syrjälä
Intel
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