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

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: igt-dev@lists.freedesktop.org,
	Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	eben@raspberrypi.org
Subject: Re: [igt-dev] [PATCH v3 03/11] fb: Add format conversion routine
Date: Mon, 4 Jun 2018 13:13:53 +0300	[thread overview]
Message-ID: <20180604101353.GB23723@intel.com> (raw)
In-Reply-To: <20180604095403.fvfz5ygb4jfq73m4@flea>

On Mon, Jun 04, 2018 at 11:54:03AM +0200, Maxime Ripard wrote:
> 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.

The current thing (and my patches) converts both ways. Can't get much
more generic than that.

> 
> And that buffer cannot be created by cairo,

Why not?

> 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

-- 
Ville Syrjälä
Intel
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