linux-kernel - Re: [PATCH] drm/i915/vlv: Prevent enabling hpd polling in late suspend

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Date:   Wed, 26 Oct 2016 19:50:25 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Lyude <lyude@...hat.com>
Cc:     intel-gfx@...ts.freedesktop.org,
        Jani Saarinen <jani.saarinen@...el.com>,
        Petry Latvala <petri.latvala@...el.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/i915/vlv: Prevent enabling hpd polling in late
 suspend

On Wed, Oct 26, 2016 at 12:36:09PM -0400, Lyude wrote:
> One of the CI machines began to run into issues with the hpd poller
> suddenly waking up in the midst of the late suspend phase. It looks like
> this is getting caused by the fact we now deinitialize power wells in
> late suspend, which means that intel_hpd_poll_init() gets called in late
> suspend causing polling to get re-enabled. So, when deinitializing power
> wells on valleyview we now refrain from enabling polling in the midst of
> suspend.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98040
> Fixes: 19625e85c6ec ("drm/i915: Enable polling when we don't have hpd")
> Signed-off-by: Lyude <lyude@...hat.com>
> Cc: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> Cc: Jani Saarinen <jani.saarinen@...el.com>
> Cc: Petry Latvala <petri.latvala@...el.com>
> ---
>  drivers/gpu/drm/i915/intel_runtime_pm.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 82edba2..ac85482 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -1138,7 +1138,9 @@ static void vlv_display_power_well_deinit(struct drm_i915_private *dev_priv)
>  
>  	intel_power_sequencer_reset(dev_priv);
>  
> -	intel_hpd_poll_init(dev_priv);
> +	/* Prevent us from re-enabling polling on accident in late suspend */
> +	if (!dev_priv->drm.dev->power.is_suspended)
> +		intel_hpd_poll_init(dev_priv);

The flag would appear to get set between suspend and suspend_late, so
looks like this should be sufficient for our purposes.

Reviewed-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>

>  }
>  
>  static void vlv_display_power_well_enable(struct drm_i915_private *dev_priv,
> -- 
> 2.7.4

-- 
Ville Syrjälä
Intel OTC