On 27 June 2017 at 20:43, Kenneth Graunke <kenn...@whitecape.org> wrote:
> On Tuesday, June 27, 2017 11:00:48 AM PDT Chad Versace wrote:
>> The Android framework requires support for EGLConfigs with
>> HAL_PIXEL_FORMAT_RGBX_8888 and HAL_PIXEL_FORMAT_RGBA_8888.
>>
>> Even though all RGBX formats are disabled on gen9 by
>> brw_surface_formats.c, the new configs work correctly on Broxton thanks
>> to _mesa_format_fallback_rgbx_to_rgba().
>>
>> On GLX, this creates no new configs, and therefore breaks no existing
>> apps. See in-patch comments for explanation. I tested with glxinfo and
>> glxgears on Skylake.
>>
>> On Wayland, this also creates no new configs, and therfore breaks no
>> existing apps. (I tested with mesa-demos' eglinfo and es2gears_wayland
>> on Skylake). The reason differs from GLX, though. In
>> dri2_wl_add_configs_for_visual(), the format table contains only
>> B8G8R8X8, B8G8R8A8, and B5G6B5; and dri2_add_config() correctly matches
>> EGLConfig to format by inspecting channel masks.
>>
>> On Android, in Chrome OS, I tested this on a Broxton device. I confirmed
>> that the Google Play Store's EGLSurface used HAL_PIXEL_FORMAT_RGBA_8888,
>> and that an Asteroid game's EGLSurface used HAL_PIXEL_FORMAT_RGBX_8888.
>> Both apps worked well. (Disclaimer: I didn't test this patch on Android
>> with Mesa master. I backported this patch series to an older Android
>> branch).
>> ---
>> src/mesa/drivers/dri/i965/intel_fbo.c | 23 +++++++++++++++++++++--
>> src/mesa/drivers/dri/i965/intel_screen.c | 23 ++++++++++++++++++++++-
>> 2 files changed, 43 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/intel_fbo.c
>> b/src/mesa/drivers/dri/i965/intel_fbo.c
>> index caf182ca8b7..b59fc1fc7d0 100644
>> --- a/src/mesa/drivers/dri/i965/intel_fbo.c
>> +++ b/src/mesa/drivers/dri/i965/intel_fbo.c
>> @@ -450,10 +450,29 @@ intel_create_winsys_renderbuffer(struct intel_screen
>> *screen,
>>
>> _mesa_init_renderbuffer(rb, 0);
>> rb->ClassID = INTEL_RB_CLASS;
>> + rb->NumSamples = num_samples;
>> +
>> + /* The base format and internal format must be derived from the
>> user-visible
>> + * format (that is, the gl_config's format), even if we internally use
>> + * choose a different format for the renderbuffer. Otherwise, rendering
>> may
>> + * use incorrect channel write masks.
>> + */
>> rb->_BaseFormat = _mesa_get_format_base_format(format);
>> - rb->Format = format;
>> rb->InternalFormat = rb->_BaseFormat;
>> - rb->NumSamples = num_samples;
>> +
>> + rb->Format = format;
>> + if (!screen->mesa_format_supports_render[rb->Format]) {
>> + /* The glRenderbufferStorage paths in core Mesa detect if the driver
>> + * does not support the user-requested format, and then searches for
>> + * a falback format. The DRI code bypasses core Mesa, though. So we do
>> + * the fallbacks here.
>> + *
>> + * We must support MESA_FORMAT_R8G8B8X8 on Android because the Android
>> + * framework requires HAL_PIXEL_FORMAT_RGBX8888 winsys surfaces.
>> + */
>> + rb->Format = _mesa_format_fallback_rgbx_to_rgba(rb->Format);
>> + assert(screen->mesa_format_supports_render[rb->Format]);
>> + }
>>
>> /* intel-specific methods */
>> rb->Delete = intel_delete_renderbuffer;
>> diff --git a/src/mesa/drivers/dri/i965/intel_screen.c
>> b/src/mesa/drivers/dri/i965/intel_screen.c
>> index 8621af26378..0e03c56cf88 100644
>> --- a/src/mesa/drivers/dri/i965/intel_screen.c
>> +++ b/src/mesa/drivers/dri/i965/intel_screen.c
>> @@ -1717,7 +1717,28 @@ intel_screen_make_configs(__DRIscreen *dri_screen)
>> static const mesa_format formats[] = {
>> MESA_FORMAT_B5G6R5_UNORM,
>> MESA_FORMAT_B8G8R8A8_UNORM,
>> - MESA_FORMAT_B8G8R8X8_UNORM
>> + MESA_FORMAT_B8G8R8X8_UNORM,
>> +
>> + /* The 32-bit RGBA format must not precede the 32-bit BGRA format.
>> + * Likewise for RGBX and BGRX. Otherwise, the GLX client and the GLX
>> + * server may disagree on which format the GLXFBConfig represents,
>> + * resulting in swapped color channels.
>> + *
>> + * The problem, as of 2017-05-30:
>> + * When matching a GLXFBConfig to a __DRIconfig, GLX ignores the
>> channel
>> + * order and chooses the first __DRIconfig with the expected channel
>> + * sizes. Specifically, GLX compares the GLXFBConfig's and
>> __DRIconfig's
>> + * __DRI_ATTRIB_{CHANNEL}_SIZE but ignores
>> __DRI_ATTRIB_{CHANNEL}_MASK.
>
> The series is:
> Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
>
Fwiw form me
Reviewed-by: Emil Velikov <emil.veli...@collabora.com>
> But, I still think this should be fixed. This seems fragile - we're
> essentially relying on a bug in the GLX code.
>
I have some patches that add MASK checking/parsing in libGL (it's
completely ignored since code was introduced) analogous to libEGL.
Although will need to check if X needs similar fix.
> I suppose fixing it would cause GLX to begin exposing new RGBA visuals
> (in addition to BGRA). I don't think we want to do that - I don't see much
> point outside of Android. It's mostly harmless, except that changing the
> visuals ends up being absurdly painful for driver developers, since the X
> server and clients need to agree on lists. That means you can't move across
> the change point without updating the Mesa your X server uses and restarting
> the X server.
>
> If we do fix GLX, and want to avoid exposing visuals, I think we could
> easily add an #ifdef ANDROID. Is there some reason to not go ahead and
> do that now?
>
FWIW I wasn't too excited about adding more Android workarounds, since
nobody was addressing the existing ones :-(
With handful of those fixed (thanks Rob!) - feel free to add a guard.
> Also...did we fix the visual ordering problem? Earlier you mentioned that
> this patch wouldn't work for Android, because we needed to move the RGBA
> formats above the BGRA ones (but that wouldn't work for X). But I think
> you said you had EGL patches which fixed that, and I'm pretty sure those
> landed. So...we're good now?
>
Yes it did - it's a common misuse of {egl/glX}ChooseConfig + pick the first one.
On second though - one may be able to address in the Android frontend
library. It can call the vendor library, fetching all the configs,
sort, filter + apply other heuristics as needed and then feed the
result back to the user. But that for another day.
Regards,
Emil
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