On Sun, Jul 14, 2013 at 09:56:45PM +0400, Konstantin Khlebnikov wrote:
> Daniel Vetter wrote:
> >On Sun, Jul 14, 2013 at 6:30 PM, Konstantin Khlebnikov
> ><
khlebnikov@openvz.org> wrote:
> >>This patch fixes regression in power consumtion of sandy bridge gpu, which
> >>exists since v3.6 Sometimes after resuming from s2ram gpu starts thinking that
> >>it's extremely busy. After that it never reaches rc6 state.
> >>
> >>Bug was introduce by commit b4ae3f22d238617ca11610b29fde16cf8c0bc6e0
> >>("drm/i915: load boot context at driver init time"). Without documentation
> >>it's not clear what is happening here, probably this breaks internal state of
> >>hardware ring buffers and confuses RPS engine. Fortunately keeping forcewake
> >>during whole initialization sequence in gen6_init_clock_gating() fixes this bug.
> >>
> >>References:
https://bugs.freedesktop.org/show_bug.cgi?id=54089
> >>Signed-off-by: Konstantin Khlebnikov<
khlebnikov@openvz.org>
> >
> >We already hold an forcewake reference while setting up the rps stuff,
> >should we maybe hold the forcewake for the entire duration, i.e. grab
> >it here in clock_gating and release it only in gen6/vlv_enable_rps?
> >Can you please test that version, too?
>
> This will be racy because rps stuff is done in separate work which might be canceled
> if intel_disable_gt_powersave() happens before its completion.