[Mesa-dev] [PATCH v2] dri/i965: fix incorrect rgbFormat in intelCreateBuffer().

[Ilia Mirkin]

On Tue, Apr 5, 2016 at 4:57 PM, Haixia Shi <hshi at chromium.org> wrote:
> CC Stephane
>
> In my opinion we should not assume sRGB-capable when alpha is requested,
> because UNORM is the more common use case. I actually have a use case where
> alpha is requested but not sRGBCapable, and if we assume SRGB by default
> then we will get really white-washed faded color.

That most likely means that your application is buggy. Even though the
SRGB format is returned internally, that doesn't mean that SRGB
encoding/decoding is actually enabled. Just provides the option for it
to be used.

>
> On Tue, Apr 5, 2016 at 1:52 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>
>> On Tue, Apr 5, 2016 at 4:33 PM, Haixia Shi <hshi at chromium.org> wrote:
>> > It is incorrect to assume that pixel format is always in BGR byte order.
>> > We need to check bitmask parameters (such as |redMask|) to determine
>> > whether
>> > the RGB or BGR byte order is requested.
>> >
>> > Furthermore when parameter |sRGBCapable| is set to false, we should be
>> > using
>> > UNORM format by default.
>>
>> Unfortunately none of the visuals are exported with that flag, so it
>> will always be false in practice. The current logic is also very
>> fragile -- you only get a sRGB-capable fb if you happen to request
>> alpha.
>>
>> >
>> > v2: reformat code to stay within 80 character per line limit.
>> >
>> > Signed-off-by: Haixia Shi <hshi at chromium.org>
>> > Reviewed-by: Stéphane Marchesin <marcheu at chromium.org>
>> > Cc: kenneth.w.graunke at intel.com
>> >
>> > Change-Id: Ib75087aef1fbfb51baa72517207fed410dcd7b1e
>> > ---
>> >  src/mesa/drivers/dri/i965/intel_screen.c | 20 ++++++++++++--------
>> >  1 file changed, 12 insertions(+), 8 deletions(-)
>> >
>> > diff --git a/src/mesa/drivers/dri/i965/intel_screen.c
>> > b/src/mesa/drivers/dri/i965/intel_screen.c
>> > index c6eb50a..a27d7ee 100644
>> > --- a/src/mesa/drivers/dri/i965/intel_screen.c
>> > +++ b/src/mesa/drivers/dri/i965/intel_screen.c
>> > @@ -1000,15 +1000,19 @@ intelCreateBuffer(__DRIscreen * driScrnPriv,
>> >        fb->Visual.samples = num_samples;
>> >     }
>> >
>> > -   if (mesaVis->redBits == 5)
>> > -      rgbFormat = MESA_FORMAT_B5G6R5_UNORM;
>> > -   else if (mesaVis->sRGBCapable)
>> > -      rgbFormat = MESA_FORMAT_B8G8R8A8_SRGB;
>> > -   else if (mesaVis->alphaBits == 0)
>> > -      rgbFormat = MESA_FORMAT_B8G8R8X8_UNORM;
>> > -   else {
>> > -      rgbFormat = MESA_FORMAT_B8G8R8A8_SRGB;
>> > +   if (mesaVis->redBits == 5) {
>> > +      rgbFormat = mesaVis->redMask == 0x1f ? MESA_FORMAT_R5G6B5_UNORM
>> > +                                           : MESA_FORMAT_B5G6R5_UNORM;
>> > +   } else if (mesaVis->alphaBits == 0) {
>> > +      rgbFormat = mesaVis->redMask == 0xff ? MESA_FORMAT_R8G8B8X8_UNORM
>> > +                                           :
>> > MESA_FORMAT_B8G8R8X8_UNORM;
>> > +   } else if (mesaVis->sRGBCapable) {
>> > +      rgbFormat = mesaVis->redMask == 0xff ? MESA_FORMAT_R8G8B8A8_SRGB
>> > +                                           : MESA_FORMAT_B8G8R8A8_SRGB;
>> >        fb->Visual.sRGBCapable = true;
>> > +   } else {
>> > +      rgbFormat = mesaVis->redMask == 0xff ? MESA_FORMAT_R8G8B8A8_UNORM
>> > +                                           :
>> > MESA_FORMAT_B8G8R8A8_UNORM;
>> >     }
>> >
>> >     /* setup the hardware-based renderbuffers */
>> > --
>> > 2.8.0.rc3.226.g39d4020
>> >
>> > _______________________________________________
>> > mesa-dev mailing list
>> > mesa-dev at lists.freedesktop.org
>> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
>