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.
--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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