On Mon, Mar 5, 2018 at 7:33 AM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > On Mon, Mar 5, 2018 at 1:17 AM, Mario Kleiner > <mario.kleiner...@gmail.com> wrote: >> On 03/03/2018 12:59 AM, Ilia Mirkin wrote: >>> >>> On Fri, Mar 2, 2018 at 6:46 PM, Mario Kleiner >>> <mario.kleiner...@gmail.com> wrote: >>>> >>>> On 03/02/2018 11:29 PM, Ilia Mirkin wrote: >>>>> >>>>> OK, so even if you're passing 1024 to xf86HandleColormaps, gamma_set >>>>> still only gets called with a 256-entry LUT? If so, that works nicely >>>>> here, but is not intuitive :) >>>> >>>> >>>> Yes. Lots of remapping in the server, i get dizzy everytime i look at it, >>>> and forget almost immediately how stuff fits together when i don't look >>>> at >>>> it. Anyway, the final downsampling from 1024 -> 256 hw lut happens in >>>> xf86RandR12CrtcComputeGamma(), see >>>> >>>> >>>> https://cgit.freedesktop.org/xorg/xserver/commit/?id=b5f9fcd50a999a00128c0cc3f6e7d1f66182c9d5 >>>> >>>> for the latest. I'll propose that one to get cherry-picked into the >>>> server-1.19 branch as well. >>> >>> >>> Hrmph. That means we should try to adjust the gamma_set helper to do >>> the sampling when receiving a 1024-sized LUT, if people will use older >>> X servers (seems likely). Should hopefully be straightforward, to >>> handle just that one case. >> >> >> I think we never receive anything but a 256 slot LUT via gamma_set afaics? >> The server initializes xf86Crtc's gamma_size to 256 at startup, and none of >> the ddx'es ever overrides that with actual info from the kernel. >> >> What happens on older servers without that patch iff color depth 30 is >> selected is simply that the gamma table updates no-op, so the server runs >> with an identity gamma table setup at startup. Not perfect, but also not >> that bad, given that probably most people run their setups with a gamma of >> 1.0 anyway. At default depth 24 stuff works as usual. > > Ah OK. That's not so bad. I'll try to play around with it this week. > Thanks for the explanation!
I just tested this out against xorg 1.19.5. With your patch, I get an extremely dark screen. I think it's just getting the first 256 of the 1024 values (I checked -- gamma_set is still only getting 256 values). So we have to do something a bit cleverer to fix this scenario... ideas? -ilia _______________________________________________ Nouveau mailing list Nouveau@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/nouveau
