Re: [PATCH 1/4] drm/i915: Force PSR exit when IRQ_HPD is detected on eDP.

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Nov 11, 2015 at 01:19:58PM -0800, Rodrigo Vivi wrote:
> According to VESA spec: "If a Source device receives and IRQ_HPD
> while in a PSR active state, and cannot identify what caused the
> IRQ_HPD to be generated, based on Sink device status registers,
> the Source device can take implementation-specific action.
> One such action can be to exit and then re-enter a PSR active
> state."
> 
> Since we aren't checking for any sink status registers and we
>  aren't looking for any other implementation-specific action,
> in case we receive any IRQ_HPD and psr is active let's force
> the exit and reschedule it back.
> 
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c  |  5 ++++-
>  drivers/gpu/drm/i915/intel_drv.h |  1 +
>  drivers/gpu/drm/i915/intel_psr.c | 33 +++++++++++++++++++++++++++++++++
>  3 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 99b7f1d..71911b9 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4892,6 +4892,8 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>  
>  	if (intel_dig_port->base.type != INTEL_OUTPUT_EDP)
>  		intel_dig_port->base.type = INTEL_OUTPUT_DISPLAYPORT;
> +	else
> +		intel_psr_irq_hpd(dev);

IRQ_HPD means short HPD. This one is now done for long HPD too. And in
any case the placement is a bit weird since now the two branches here
are totally unrelated.

>  
>  	if (long_hpd && intel_dig_port->base.type == INTEL_OUTPUT_EDP) {
>  		/*
> @@ -4900,8 +4902,9 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>  		 * would end up in an endless cycle of
>  		 * "vdd off -> long hpd -> vdd on -> detect -> vdd off -> ..."
>  		 */
> -		DRM_DEBUG_KMS("ignoring long hpd on eDP port %c\n",
> +		DRM_DEBUG_KMS("long hpd on eDP port %c\n",
>  			      port_name(intel_dig_port->port));
> +
>  		return IRQ_HANDLED;
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index e3794d3..95242e6 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1411,6 +1411,7 @@ void intel_psr_flush(struct drm_device *dev,
>  void intel_psr_init(struct drm_device *dev);
>  void intel_psr_single_frame_update(struct drm_device *dev,
>  				   unsigned frontbuffer_bits);
> +void intel_psr_irq_hpd(struct drm_device *dev);
>  
>  /* intel_runtime_pm.c */
>  int intel_power_domains_init(struct drm_i915_private *);
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index 213581c..e5ae844 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -741,6 +741,39 @@ void intel_psr_flush(struct drm_device *dev,
>  }
>  
>  /**
> + * intel_psr_irq_hpd - Let PSR aware of IRQ_HPD
> + * @dev: DRM device
> + *
> + * This function is called when IRQ_HPD is received on eDP.
> + */
> +void intel_psr_irq_hpd(struct drm_device *dev)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	int delay_ms = HAS_DDI(dev) ? 100 : 500;
> +
> +	mutex_lock(&dev_priv->psr.lock);
> +
> +	/*
> +	 * According to VESA spec "If a Source device receives and IRQ_HPD
> +	 * while in a PSR active state, and cannot identify what caused the
> +	 * IRQ_HPD to be generated, based on Sink device status registers,
> +	 * the Source device can take implementation-specific action.
> +	 * One such action can be to exit and then re-enter a PSR active
> +	 * state." Since we aren't checking for any sink status registers
> +	 * and we aren't looking for any other implementation-specific
> +	 * action, in case we receive any IRQ_HPD and psr is active let's
> +	 * force the exit and reschedule it back.
> +	 */
> +	if (dev_priv->psr.active) {
> +		intel_psr_exit(dev);
> +		schedule_delayed_work(&dev_priv->psr.work,
> +				      msecs_to_jiffies(delay_ms));
> +	}
> +
> +	mutex_unlock(&dev_priv->psr.lock);
> +}
> +
> +/**
>   * intel_psr_init - Init basic PSR work and mutex.
>   * @dev: DRM device
>   *
> -- 
> 2.4.3
> 
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-- 
Ville Syrjälä
Intel OTC
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