[igt-dev] [PATCH v3 03/11] fb: Add format conversion routine

[Maxime Ripard]

On Thu, May 24, 2018 at 06:40:36PM +0300, Ville Syrjälä wrote:
> On Thu, May 24, 2018 at 05:19:04PM +0200, Maxime Ripard wrote:
> > On Thu, May 24, 2018 at 05:58:13PM +0300, Ville Syrjälä wrote:
> > > On Thu, May 24, 2018 at 04:24:42PM +0200, Maxime Ripard wrote:
> > > > The chamelium format subtests will need to convert the reference pattern to
> > > > the format to be tested on the DRM device.
> > > > 
> > > > However, Cairo is very limited when it comes to format, and while pixman
> > > > has much more support for formats, it's still falling short compared to
> > > > what DRM exposes, especially on the YUV side.
> > > 
> > > We already have the capability to do format conversions automagically.
> > > I'm extending it to handle more YUV stuff here:
> > > https://patchwork.freedesktop.org/series/43651/
> > > 
> > > Can you hook up the pixman stuff in the same way so that we don't
> > > have to any explicit conversion stuff in the tests themselves?
> > 
> > I really think that the assumption that cairo will handle it is not a
> > proper fit. Cairo support is very limited, just like pixman is to a
> > lesser extent, and we should just break the assumption that we will
> > get a cairo surface all the time.
> 
> Not sure what you're saying here. We don't assume cairo handles all
> the formats, well, because it doesn't. We just magically convert
> to/from XRGB888 so that cairo doesn't have to handle anything else.

My point was that from what I can tell from your patches, you allow to
create an igt_fb with whatever format we want, and then convert it to
XRGB8888 when one calls igt_get_cairo_surface.

I need something more generic, but even if we simplify to the
operation that I need now, I basically needs the exact opposite: to be
able to take an XRGB8888 buffer (that is our pattern) and get an
igt_fb in an arbitrary format.

And that buffer cannot be created by cairo, so relying on the
destroy_cairo_surface__convert to convert it back from XRGB8888 to
whatever format doesn't work.

So yeah, we can't really rely on cairo in this particuliar case, and
the buffer conversions need be to made explicit.

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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