Re: [PATCH v5 6/6] drm/i915/crt: Use intel_hpd_block/unblock() instead of intel_hpd_disable/enable()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 04 Mar 2025, Imre Deak <imre.deak@intel.com> wrote:
> intel_hpd_disable/enable() have the same purpose as
> intel_hpd_block/unblock(), except that disable/enable will drop any HPD
> IRQs which were triggered while the HPD was disabled, while
> block/unblock will handle such IRQs after the IRQ handling is unblocked.
> Use intel_hpd_block/unblock() for crt as well, by adding a helper to
> explicitly clear any pending IRQs before unblocking.
>
> v2:
> - Handle encoders without a port assigned to them.
> - Rebase on change in intel_hpd_suspend() documentation.
> v3:
> - Rebase on the suspend/resume -> block/unblock rename change.
> - Clear the pending events only after all encoders have unblocked the
>   HPD handling.
> - Clear the short/long port events for all encoders using the given HPD
>   pin.
> v4:
> - Rebase on port->hpd_pin tracking. (Ville)
>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_crt.c     |  7 +--
>  drivers/gpu/drm/i915/display/intel_hotplug.c | 60 +++++++++++---------
>  drivers/gpu/drm/i915/display/intel_hotplug.h |  3 +-
>  3 files changed, 35 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_crt.c b/drivers/gpu/drm/i915/display/intel_crt.c
> index 76ffb3f8467c8..bca91d49cb960 100644
> --- a/drivers/gpu/drm/i915/display/intel_crt.c
> +++ b/drivers/gpu/drm/i915/display/intel_crt.c
> @@ -532,8 +532,6 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
>  {
>  	struct intel_display *display = to_intel_display(connector->dev);
>  	struct intel_crt *crt = intel_attached_crt(to_intel_connector(connector));
> -	struct drm_i915_private *dev_priv = to_i915(connector->dev);
> -	bool reenable_hpd;
>  	u32 adpa;
>  	bool ret;
>  	u32 save_adpa;
> @@ -550,7 +548,7 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
>  	 *
>  	 * Just disable HPD interrupts here to prevent this
>  	 */
> -	reenable_hpd = intel_hpd_disable(dev_priv, crt->base.hpd_pin);
> +	intel_hpd_block(&crt->base);
>  
>  	save_adpa = adpa = intel_de_read(display, crt->adpa_reg);
>  	drm_dbg_kms(display->drm,
> @@ -577,8 +575,7 @@ static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
>  	drm_dbg_kms(display->drm,
>  		    "valleyview hotplug adpa=0x%x, result %d\n", adpa, ret);
>  
> -	if (reenable_hpd)
> -		intel_hpd_enable(dev_priv, crt->base.hpd_pin);
> +	intel_hpd_clear_and_unblock(&crt->base);
>  
>  	return ret;
>  }
> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.c b/drivers/gpu/drm/i915/display/intel_hotplug.c
> index cb4e320a1023d..423925fec73dc 100644
> --- a/drivers/gpu/drm/i915/display/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/display/intel_hotplug.c
> @@ -993,33 +993,6 @@ void intel_hpd_cancel_work(struct drm_i915_private *dev_priv)
>  		drm_dbg_kms(&dev_priv->drm, "Hotplug detection work still active\n");
>  }
>  
> -bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
> -{
> -	bool ret = false;
> -
> -	if (pin == HPD_NONE)
> -		return false;
> -
> -	spin_lock_irq(&dev_priv->irq_lock);
> -	if (dev_priv->display.hotplug.stats[pin].state == HPD_ENABLED) {
> -		dev_priv->display.hotplug.stats[pin].state = HPD_DISABLED;
> -		ret = true;
> -	}
> -	spin_unlock_irq(&dev_priv->irq_lock);
> -
> -	return ret;
> -}
> -
> -void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin)
> -{
> -	if (pin == HPD_NONE)
> -		return;
> -
> -	spin_lock_irq(&dev_priv->irq_lock);
> -	dev_priv->display.hotplug.stats[pin].state = HPD_ENABLED;
> -	spin_unlock_irq(&dev_priv->irq_lock);
> -}
> -
>  static void queue_work_for_missed_irqs(struct drm_i915_private *i915)
>  {
>  	struct intel_display *display = to_intel_display(&i915->drm);
> @@ -1096,7 +1069,8 @@ static bool unblock_hpd_pin(struct intel_display *display, enum hpd_pin pin)
>   *   drm_connector_funcs::detect()) remains allowed, for instance as part of
>   *   userspace connector probing, or DRM core's connector polling.
>   *
> - * The call must be followed by calling intel_hpd_unblock().
> + * The call must be followed by calling intel_hpd_unblock(), or
> + * intel_hpd_clear_and_unblock().
>   *
>   * Note that the handling of HPD IRQs for another encoder using the same HPD
>   * pin as that of @encoder will be also blocked.
> @@ -1147,6 +1121,36 @@ void intel_hpd_unblock(struct intel_encoder *encoder)
>  	spin_unlock_irq(&i915->irq_lock);
>  }
>  
> +/**
> + * intel_hpd_clear_and_unblock - Unblock handling of new HPD IRQs on an HPD pin
> + * @encoder: Encoder to unblock the HPD handling for
> + *
> + * Unblock the handling of HPD IRQs on the HPD pin of @encoder, which was
> + * previously blocked by intel_hpd_block(). Any HPD IRQ raised on the
> + * HPD pin while it was blocked will be cleared, handling only new IRQs.
> + */
> +void intel_hpd_clear_and_unblock(struct intel_encoder *encoder)
> +{
> +	struct intel_display *display = to_intel_display(encoder);
> +	struct drm_i915_private *i915 = to_i915(display->drm);
> +	struct intel_hotplug *hotplug = &display->hotplug;
> +	enum hpd_pin pin = encoder->hpd_pin;
> +
> +	if (pin == HPD_NONE)
> +		return;
> +
> +	spin_lock_irq(&i915->irq_lock);
> +
> +	if (unblock_hpd_pin(display, pin)) {
> +		hotplug->event_bits &= ~BIT(pin);
> +		hotplug->retry_bits &= ~BIT(pin);
> +		hotplug->short_hpd_pin_mask &= ~BIT(pin);
> +		hotplug->long_hpd_pin_mask &= ~BIT(pin);
> +	}
> +
> +	spin_unlock_irq(&i915->irq_lock);
> +}
> +
>  void intel_hpd_enable_detection_work(struct drm_i915_private *i915)
>  {
>  	spin_lock_irq(&i915->irq_lock);
> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.h b/drivers/gpu/drm/i915/display/intel_hotplug.h
> index 5f9857136f5e3..f189b871904ed 100644
> --- a/drivers/gpu/drm/i915/display/intel_hotplug.h
> +++ b/drivers/gpu/drm/i915/display/intel_hotplug.h
> @@ -26,10 +26,9 @@ void intel_hpd_init(struct drm_i915_private *dev_priv);
>  void intel_hpd_init_early(struct drm_i915_private *i915);
>  void intel_hpd_cancel_work(struct drm_i915_private *dev_priv);
>  enum hpd_pin intel_hpd_pin_default(enum port port);
> -bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
> -void intel_hpd_enable(struct drm_i915_private *dev_priv, enum hpd_pin pin);
>  void intel_hpd_block(struct intel_encoder *encoder);
>  void intel_hpd_unblock(struct intel_encoder *encoder);
> +void intel_hpd_clear_and_unblock(struct intel_encoder *encoder);
>  void intel_hpd_debugfs_register(struct drm_i915_private *i915);
>  
>  void intel_hpd_enable_detection_work(struct drm_i915_private *i915);

-- 
Jani Nikula, Intel