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Bug 3792

Summary: [KMS/DRM] Wrong GBM format
Product: SDL Reporter: Romain Tisserand <romain.tisserand>
Component: videoAssignee: Brandon Schaefer <brandontschaefer>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: HG 2.0   
Hardware: All   
OS: Linux   

Description Romain Tisserand 2017-09-01 09:58:10 UTC 
Using KMS/DRM driver from WIP SDL2.0.6 on Linux/ARM SoC RockChip RK3328 (ARM Mali 450 MP2 GPU).

The current code is using GBM_BO_FORMAT_XRGB8888 as GBM buffer format specifier.

The Mali driver (it has been confirmed some other vendor implementations too) expects GBM_FORMAT_XRGB8888.

The Mesa implementation is actually handling both values as the same, but it's not implemented like this into every gbm.h vendor header.

https://github.com/ideak/mesa/blob/master/src/gbm/backends/dri/gbm_dri.c

So with stock SDL2 on my card (Mali vendor implementation), it does not work, eglCreateWindowSurface fails, and gbm_is_format_supported fails too (with the BO variant).
It runs fine with GBM_FORMAT_XRGB8888.

Here is a link of the gbm.h from Mali user-space driver :

https://github.com/rockchip-linux/libmali/blob/rockchip/include/gbm.h
Comment 1 Sam Lantinga 2017-09-01 17:26:56 UTC 
Brandon, can you look at this and push a patch if appropriate?

Thanks!
Comment 2 Brandon Schaefer 2017-09-01 18:18:47 UTC 
Yup! Was looking into it, but seems most usages of gbm_surface_create I see end up using GBM_BO_FORMAT_XRGB8888. Though Ive only ever tested things out on mesa :)

If the mesa driver seems to handle both I dont see an issue pushing that change. Ill test on the devices I have (raspi3/x86) to double check and Ill chase down if its possibly a driver bug in libmali not supporting that enum the same way mesa does.

Thanks again for testing this backend out!
Comment 3 Sam Lantinga 2017-09-01 19:54:11 UTC 
Fixed, thanks!
https://hg.libsdl.org/SDL/rev/11413fa29401
Comment 4 Brandon Schaefer 2017-09-01 21:00:08 UTC 
Awesome, and tested on raspi3 and intel amd64 working.

Thanks again!