On 2020-11-30 at 17:28:32 +0200, Imre Deak wrote:
> On Mon, Nov 30, 2020 at 02:46:46PM +0530, Anshuman Gupta wrote:
> > At usual case DC3CO exit happen automatically by DMC f/w whenever
> > PSR2 clears idle. This happens smoothly by DMC f/w to work with flips.
> > But there are certain scenario where DC3CO Disallowed by driver
> > asynchronous with flips. In such scenario display engine could
> > be already in DC3CO state and driver has disallowed it,
> > It initiates DC3CO exit sequence in DMC f/w which requires a
> > dc3co exit delay of 200us in driver.
> > It requires to protect intel_pipe_update_{update_end} with
> > dc3co exit delay.
> >
> > Cc: Imre Deak <imre.deak@xxxxxxxxx>
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Anshuman Gupta <anshuman.gupta@xxxxxxxxx>
>
> To make sure that it doesn't hide the root cause (or affects unrelated
> platforms), I'd only add locking around DC3co changes with a new lock,
> using lock/unlock helpers in intel_display_power.c called from
> intel_pipe_update_start/end.
>
> Also please submit this patch separately, w/o the optimization in patch
> 1/2, so we know that this change fixes the problem.
Thanks imre for review comments, i will send a new patch with review comments fixed.
Anshuman Gupta.
>
> --Imre
>
> > ---
> > drivers/gpu/drm/i915/display/intel_display.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index ba26545392bc..3b81b98c0daf 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -15924,6 +15924,8 @@ static void intel_update_crtc(struct intel_atomic_state *state,
> > else
> > intel_fbc_enable(state, crtc);
> >
> > + /* Protect intel_pipe_update_{start,end} with power_domians lock */
> > + mutex_lock(&dev_priv->power_domains.lock);
> > /* Perform vblank evasion around commit operation */
> > intel_pipe_update_start(new_crtc_state);
> >
> > @@ -15935,6 +15937,7 @@ static void intel_update_crtc(struct intel_atomic_state *state,
> > i9xx_update_planes_on_crtc(state, crtc);
> >
> > intel_pipe_update_end(new_crtc_state);
> > + mutex_unlock(&dev_prive->power_domains.lock);
> >
> > /*
> > * We usually enable FIFO underrun interrupts as part of the
> > --
> > 2.26.2
> >
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