On Fri, Nov 13, 2015 at 06:20:00PM +0000, Daniel Stone wrote: > Hi Rodrigo, > > On 5 November 2015 at 18:49, Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> wrote: > > With this we know if IPS is actually enabled. > > It might not be activated on BDW since Hardware take > > the decision and do its transition. However we have > > the visibility of the state on our driver what we didn't > > had until this patch. At least on BDW. > > > > Since ips_ready means that ips will be enabled and ips_disable() > > checks for the state of our enabled/disabled state machine > > we can remove that FIXME that was there for crtc_load_lut > > workaround for Haswell. > > > > With this state machine and ips being disabled from > > different places and many times when testcases with sink_crtc > > for instance it is better to have it protected with its own mutex lock. > > Ohterwise we cannot guarantee consitent ips.enabled state with the > > register bit. > > Thinking about this, I have two comments (and second Chris's > similar-ish comment about PSR): > > Should this perhaps be a CRTC property rather than a device property? > Is it tied to a particular pipe, or can it move away from pipe A? > > Secondly, having a vblank wait to enable IPS is pretty unfortunate, as > it makes modesets take longer. I like the PSR enable being split away > from the modeset sequence, so perhaps we could do something like: > > enum ips_state { > IPS_DISABLED = 0, /**< unsupported or explicitly disabled by module param */ > IPS_READY, /**< IPS can be enabled if a suitable state is applied to > the CRTC (planes enabled, cdclk not exceeding 95% on BDW) */ > IPS_ARMED, /**< suitable configuration applied; IPS pending activation */ > IPS_ACTIVE > }; > > Having this on the CRTC state means that we could walk through the > following process: > - IPS_READY set on suitable platforms when not explictly disabled > - modeset arrives: atomic_check examines conditions and changes > state from IPS_READY to IPS_ARMED > - next pageflip arrives and changes state from IPS_ARMED to > IPS_ACTIVE, activates IPS > > Being a member of the CRTC state means that anyone duplicating the > pipe's CRTC state could discover the IPS status like that, and > eliminates the need for a second mutex. > > Maybe that's not the best approach, but I think we need to find a way > to take the synchronous vblank wait out of the modeset path. Using a > workqueue is another option, but synchronisation would need to be > quite carefully handled. Long time ago I posted a patch to make ips enable asynchronously from a vblank work. -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx