Bug 99791 - Wayland EGL do not fallback to software rendering anymore when the wl_drm interface is not available
Summary: Wayland EGL do not fallback to software rendering anymore when the wl_drm int...
Status: RESOLVED FIXED
Alias: None
Product: Mesa
Classification: Unclassified
Component: EGL/Wayland (show other bugs)
Version: 17.0
Hardware: Other All
: medium major
Assignee: Wayland bug list
QA Contact: mesa-dev
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-02-13 12:05 UTC by Cédric Legrand
Modified: 2017-03-04 16:16 UTC (History)
2 users (show)

See Also:
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Description Cédric Legrand 2017-02-13 12:05:08 UTC 
Hello,

Since my system update to Mesa 17.0.0-rc3, the Wayland EGL implementation does not fallback to software rendering anymore when the wl_drm interface is not available.

After a quick look on the code, it seems that the implementation sends a WL_DRM_FORMAT_* inconditionaly, even when wl_drm is not available. Of course, this triggers an error on the server side as wl_shm does not know them:
 -> wl_display@1.error(wl_shm_pool@14, 0, "invalid format 0x34325258")

Thanks,
Cédric Legrand
Comment 1 Pekka Paalanen 2017-02-13 12:16:55 UTC 
DRM format codes are identical to wl_shm format codes, except for argb8888 and xrgb8888. It is very unfortunate to have these exceptions, but they are there.
Comment 2 Pekka Paalanen 2017-02-13 14:46:20 UTC 
I believe that the Mesa commit:

commit cb5e799448c959fa9f0d7ea76999ac6f8c0ad88e
Author: Emil Velikov <emil.velikov@collabora.com>
Date:   Mon Nov 28 18:25:19 2016 +0000

    egl/wayland: unify dri2_wl_create_surface implementations

is causing this regression by dropping the special-casing of the two formats that differ between DRM fourccs and wl_shm formats.

WL_DRM_FORMAT_XRGB8888 != WL_SHM_FORMAT_XRGB8888
WL_DRM_FORMAT_ARGB8888 != WL_SHM_FORMAT_ARGB8888
Comment 3 Daniel Stone 2017-02-13 14:58:21 UTC 
(In reply to Pekka Paalanen from comment #2)
> I believe that the Mesa commit:
> 
> commit cb5e799448c959fa9f0d7ea76999ac6f8c0ad88e
> Author: Emil Velikov <emil.velikov@collabora.com>
> Date:   Mon Nov 28 18:25:19 2016 +0000
> 
>     egl/wayland: unify dri2_wl_create_surface implementations
> 
> is causing this regression by dropping the special-casing of the two formats
> that differ between DRM fourccs and wl_shm formats.
> 
> WL_DRM_FORMAT_XRGB8888 != WL_SHM_FORMAT_XRGB8888
> WL_DRM_FORMAT_ARGB8888 != WL_SHM_FORMAT_ARGB8888

I also believe you're right, and sent this patch earlier:
https://lists.freedesktop.org/archives/mesa-dev/2017-February/144133.html

I'd attach it, but Chrome seems to be allergic to file dialogs atm.
Comment 4 Cédric Legrand 2017-02-14 11:47:56 UTC 
I applied Daniel's patch from comment #3 on Mesa 17.0.0, I can confirm that it fixes the issue, thanks a lot. Unfortunately, it did not have time to land in the final release...

I don't know if you want to close this issue now or wait for the patch to be merged, so I will let you do it.
Comment 5 Emil Velikov 2017-03-04 16:16:30 UTC 
Just realised that we forgot the bugzilla tag in the patch :-(
The following patch was merged and should address the issue.

Thanks for the help gents.

commit a1727aa75ed252cd19c296ccf83cb595be971744
Author: Daniel Stone <daniels@collabora.com>
Date:   Mon Feb 13 14:06:10 2017 +0000

    egl/wayland: Don't use DRM format codes for SHM

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