On Tue, Sep 12, 2017 at 01:57:07PM +0100, Tvrtko Ursulin wrote: > > On 12/09/2017 13:45, Tvrtko Ursulin wrote: > > > > On 12/09/2017 13:37, Chris Wilson wrote: > > > The DMC typifies the worst example of firmware: it overrides system > > > behaviour and is fubar. When no displays are active, the DMC appears to > > > continually toggle its control register trying to change display power > > > states. This in turn has the side effect of slowing down the GT by a few > > > orders of magntidue, making headless operations intolerably slow. > > > > > > This seems to affect all machines with dmc (so a byproduct of the dmc > > > code itself being shared) and severely limits throughput on the CI bxt > > > and triggers the watchdog for incomplete tests. > > > > > > Altenative suggestion is to blacklist all DMC firmware until it is > > > fixed. > > > > I've sent this as https://patchwork.freedesktop.org/patch/154942/ some > > time ago. You asked for a long code comment back then. :) > > > > Anyway, I don't mind we merge one of the two since it is taking an > > eternity to get this fixes in the firmware. So: > > > > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > I take it back, there was a reason in shape of another firmware bug which > made us put this patch on hold. Imre might know the status of that one. Yes, there is a corruption of registes in the context saved/restored during DC3->DC6 transitions. I have a test case which easily triggers this, but I was asked to produce an internal trace in addition. To set up that took me quite a while, but I got the trace now and the firwmare team is checking it. Let's see if it includes everything they hope to see. So ideally we'd wait with your W/A - which still is the correct thing - until the corruption thing is fixed. --Imre > > Regards, > > Tvrtko > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
