linux-kernel - Re: [PATCH] drm/i915: Synchronize connectors states when switching from poll to irq

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Message-ID: <1500379902.1351.7.camel@linux.intel.com>
Date:   Tue, 18 Jul 2017 15:11:42 +0300
From:   Paul Kocialkowski <paul.kocialkowski@...ux.intel.com>
To:     intel-gfx@...ts.freedesktop.org
Cc:     Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        Martin Peres <martin.peres@...ux.intel.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: Synchronize connectors states when switching
 from poll to irq

On Mon, 2017-06-26 at 15:32 +0300, Paul Kocialkowski wrote:
> After detecting an IRQ storm, hotplug detection will switch from
> irq-based detection to poll-based detection. After a short delay or
> when resetting storm detection from debugfs, detection will switch
> back to being irq-based.
> 
> However, it may occur that polling does not have enough time to detect
> the current connector state when that second switch takes place. Thus,
> this sets the appropriate hotplug event bits for the concerned
> connectors and schedules the hotplug work, that will ensure the
> connectors states are in sync when switching back to irq.
> 
> Without this, no irq will be triggered and the hpd change will be
> lost.

Does anyone have feedback to provide on this?
It looks like it should be a no-brainer.

Cheers,

Paul

> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...ux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hotplug.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c
> b/drivers/gpu/drm/i915/intel_hotplug.c
> index f1200272a699..29f55480b0bb 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -218,9 +218,13 @@ static void
> intel_hpd_irq_storm_reenable_work(struct work_struct *work)
>  			struct intel_connector *intel_connector =
> to_intel_connector(connector);
>  
>  			if (intel_connector->encoder->hpd_pin == i) {
> -				if (connector->polled !=
> intel_connector->polled)
> +				if (connector->polled !=
> intel_connector->polled) {
>  					DRM_DEBUG_DRIVER("Reenabling
> HPD on connector %s\n",
>  							 connector-
> >name);
> +
> +					dev_priv->hotplug.event_bits
> |= (1 << i);
> +				}
> +
>  				connector->polled = intel_connector-
> >polled;
>  				if (!connector->polled)
>  					connector->polled =
> DRM_CONNECTOR_POLL_HPD;
> @@ -232,6 +236,8 @@ static void
> intel_hpd_irq_storm_reenable_work(struct work_struct *work)
>  		dev_priv->display.hpd_irq_setup(dev_priv);
>  	spin_unlock_irq(&dev_priv->irq_lock);
>  
> +	schedule_work(&dev_priv->hotplug.hotplug_work);
> +
>  	intel_runtime_pm_put(dev_priv);
>  }
>  
-- 
Paul Kocialkowski <paul.kocialkowski@...ux.intel.com>
Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo, Finland