Fyi Michel, we've discussed similar issues for radeon/amdgpu on irc. On Thu, Dec 21, 2017 at 4:21 PM, Carroll, Lewis <Lewis.Carroll@xxxxxxx> wrote: >> -----Original Message----- >> From: Daniel Vetter [mailto:daniel.vetter@xxxxxxxx] On Behalf Of Daniel >> Vetter >> Sent: Thursday, December 21, 2017 5:07 AM >> To: Carroll, Lewis <Lewis.Carroll@xxxxxxx> >> Cc: Wentland, Harry <Harry.Wentland@xxxxxxx>; dri- >> devel@xxxxxxxxxxxxxxxxxxxxx >> Subject: Re: drm/ast: Linux 4.14 AST DRM driver might not load gamma table >> [patch proposed] >> >> On Thu, Dec 21, 2017 at 12:00:39AM +0000, Carroll, Lewis wrote: >> > The discussion sounds similar as well - related to load_lut() not being called. >> > >> > Perhaps after the drm-next-4.14 merge, whatever call stack used to cause >> > load_lut to always get called is now gone. Even if FB_VISUAL_TRUECOLOR >> > doesn't support a clut, some hardware may still need a default gamma lut >> > loaded (appears to be the case with the AST2500). Perhaps checking for >> > that profile and loading the default LUT prepared by >> > drm_mode_crtc_set_gamma_size when FB_VISUAL_TRUECOLOR...? >> >> Yeah drivers should load that somehow. Unfortunately I'm going on >> vacations now, so I'm not going to fix anything anytime soon. Might be >> good to ping Peter Rosin, he did all the fbdev emulation gamma handling >> rework (which is the patch that removed the superflously-looking call to >> ->load_lut that some drivers relied on to have a consistent lut state). >> -Daniel > > Enjoy the holidays. > > Wonder if it would be better to just call load_lut after > drm_mode_crtc_set_gamma_size instead of adding a potentially > unnecessary DPMS ON event to the commit call-back as I did...? Or call > load_lut in the commit callback instead of the DPMS ON call...? > > The first approach (calling load_lut after set_gamma_size) also works on > two test systems. Yeah, I think that's the cleanest approach. The underlying issue is that a bunch of drivers are not making sure that on driver-load they have a consistent sw/hw state for the gamma ramp. As long as you had fbcon enabled the strange ->load_lut call (which isn't really necessary for drivers that got this right) papered over these issues. So a call to you driver's load_lut right affter drm_mode_crtc_set_gamma_size should fix this correctly. a-b:me if you submit that patch. /me off for real now Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
