On Wed, Jun 21, 2017 at 11:40:52AM +0200, Peter Rosin wrote: > On 2017-06-21 09:38, Daniel Vetter wrote: > > On Tue, Jun 20, 2017 at 09:25:25PM +0200, Peter Rosin wrote: > >> This makes the redundant fb helpers .load_lut, .gamma_set and .gamma_get > >> totally obsolete. > >> > >> I think the gamma_store can end up invalid on error. But the way I read > >> it, that can happen in drm_mode_gamma_set_ioctl as well, so why should > >> this pesky legacy fbdev stuff be any better? > >> > >> drm_fb_helper_save_lut_atomic justs saves the gamma lut for later. However, > >> it saves it to the gamma_store which should already be up to date with what > >> .gamma_get would return and is thus a nop. So, zap it. > > > > Removing drm_fb_helper_save_lut_atomic should be a separate patch I > > think. > > Then 3 patches would be needed, first some hybrid thing that does it the > old way, but also stores the lut in .gamma_store, then the split-out that > removes drm_fb_helper_save_lut_atomic, then whatever is needed to get > to the desired code. I can certainly do that, but do you want me to? Explain that in the commit message and it's fine. > > It's a pre-existing bug, but should we also try to restore the fbdev lut > > in drm_fb_helper_restore_fbdev_mode_unlocked()? Would be yet another bug, > > but might be relevant for your use-case. Just try to run both an fbdev > > application and some kms-native thing, and then SIGKILL the native kms > > app. > > > > But since pre-existing not really required, and probably too much effort. > > Good thing too, because I don't really know my way around this code... Btw I cc'ed you on one of my patches in the fbdev locking series, we might need to do the same legacy vs. atomic split for the new lut code as I did for dpms. The rule with atomic is that you can't do multiple commits under drm_modeset_lock_all, you either have to do one overall atomic commit (preferred) or drop&reacquire locks again. This matters for LUT since you're updating the LUT on all CRTCs, which when using the gamma_set atomic helper would be multiple commits :-/ Using the dpms patch as template it shouldn't be too hard to address that for your patch here too. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
