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Happy Holidays. Test-driving Linux 4.14 from the Ubuntu Bionic repo on an AMD EPYC server using the A-Speed AST2500 BMC and the AST DRM driver and framebuffer console configured into the kernel,
I have observed multiple systems where the analog VGA color palette for the framebuffer console is incorrect. Background is blue and all text colors other than white / gray are incorrect. Instrumenting the AST DRM driver, it seems the default gamma table isn’t loaded to the silicon until there is a DPMS action. When there is a DPMS action other than DPMS OFF, the
gamma table is loaded and all is well. On these boards, the kernel is not calling for a DPMS event at driver init so the gamma table is not loaded. The attached proposed patch adds a DPMS ON event to the commit callback after a kernel modeset call. This solves the problem, however there may be a better / more proper way to
solve this. Assuming no one on the mailing list has hardware on which to verify this, I am happy to be a test driver for any suggested fixes. Regards, Lewis Carroll Principal Solutions Architect AMD Enterprise Business Group |
Attachment:
Linux_4.14_drm_ast_fix_corrupted_gamma.patch
Description: Linux_4.14_drm_ast_fix_corrupted_gamma.patch
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