[PATCH v.2 06/12] DRM/i915: Add HPD IRQ storm detection (v2)

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On Thu, Feb 28, 2013 at 04:19:15AM -0500, Egbert Eich wrote:
> Add a hotplug IRQ storm detection (triggered when a hotplug interrupt
> fires more than 5 times / sec).
> Rationale:
> Despite of the many attempts to fix the problem with noisy hotplug
> interrupt lines we are still seeing systems which have issues:
> Once cause of noise seems to be bad routing of the hotplug line
> on the board: cross talk from other signals seems to cause erronous
> hotplug interrupts. This has been documented as an erratum for the
> the i945GM chipset and thus hotplug support was disabled for this
> chipset model but others seem to have this problem, too.
> 
> We have seen this issue on a G35 motherboard for example:
> Even different motherboards of the same model seem to behave
> differently: while some only see only around 10-100 interrupts/s
> others seem to see 5k or more.
> We've also observed a dependency on the selected video mode.
> 
> Also on certain laptops interrupt noise seems to occur duing
> battery charging when the battery is at a certain charge levels.
> 
> Thus we add a simple algorithm here that detects an 'interrupt storm'
> condition.
> 
> v2: Fixed comment.
> 
> Signed-off-by: Egbert Eich <eich at suse.de>
> Acked-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_drv.h |    9 +++++
>  drivers/gpu/drm/i915/i915_irq.c |   63 +++++++++++++++++++++++++++++++-------
>  2 files changed, 60 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index d8604a6..6ca742d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1059,6 +1059,15 @@ typedef struct drm_i915_private {
>  	/* Old dri1 support infrastructure, beware the dragons ya fools entering
>  	 * here! */
>  	struct i915_dri1_state dri1;
> +	struct {
> +		unsigned long hpd_last_jiffies;
> +		int hpd_cnt;
> +		enum {
> +			HPD_ENABLED = 0,
> +			HPD_DISABLED = 1,
> +			HPD_MARK_DISABLED = 2
> +		} hpd_mark;
> +	} hpd_stats[HPD_NUM_PINS];

It's still hidden in the dri1 dungeon ;-) Imo this would fit nicely next
to the existing hotplug work and state tracking stuff.
-Daniel

>  } drm_i915_private_t;
>  
>  /* Iterate over initialised rings */
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index c40c7cc..24cb6ed 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -578,6 +578,34 @@ static void gen6_queue_rps_work(struct drm_i915_private *dev_priv,
>  	queue_work(dev_priv->wq, &dev_priv->rps.work);
>  }
>  
> +static inline void hotplug_irq_storm_detect(struct drm_device *dev,
> +					    u32 hotplug_trigger,
> +					    const u32 *hpd)
> +{
> +	drm_i915_private_t *dev_priv = dev->dev_private;
> +	unsigned long irqflags;
> +	int i;
> +
> +	spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
> +
> +	for (i = 1; i < HPD_NUM_PINS; i++) {
> +		if ((hpd[i] & hotplug_trigger) &&
> +		    dev_priv->hpd_stats[i].hpd_mark == HPD_ENABLED) {
> +			if (jiffies > (dev_priv->hpd_stats[i].hpd_last_jiffies + msecs_to_jiffies(1000)) ||
> +			    jiffies < dev_priv->hpd_stats[i].hpd_last_jiffies) {
> +				dev_priv->hpd_stats[i].hpd_last_jiffies = jiffies;
> +				dev_priv->hpd_stats[i].hpd_cnt = 0;
> +			} else if (dev_priv->hpd_stats[i].hpd_cnt > 5) {
> +				dev_priv->hpd_stats[i].hpd_mark = HPD_MARK_DISABLED;
> +				DRM_DEBUG_KMS("HPD interrupt storm detected on  PIN %d\n", i);
> +			} else
> +				dev_priv->hpd_stats[i].hpd_cnt++;
> +		}
> +	}
> +
> +	spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
> +}
> +
>  static void gmbus_irq_handler(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = (drm_i915_private_t *) dev->dev_private;
> @@ -646,13 +674,15 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg)
>  		/* Consume port.  Then clear IIR or we'll miss events */
>  		if (iir & I915_DISPLAY_PORT_INTERRUPT) {
>  			u32 hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
> +			u32 hotplug_trigger = hotplug_status & HOTPLUG_INT_STATUS_I915;
>  
>  			DRM_DEBUG_DRIVER("hotplug event received, stat 0x%08x\n",
>  					 hotplug_status);
> -			if (hotplug_status & HOTPLUG_INT_STATUS_I915)
> +			if (hotplug_trigger) {
> +				hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_status_i915);
>  				queue_work(dev_priv->wq,
>  					   &dev_priv->hotplug_work);
> -
> +			}
>  			I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
>  			I915_READ(PORT_HOTPLUG_STAT);
>  		}
> @@ -676,10 +706,12 @@ static void ibx_irq_handler(struct drm_device *dev, u32 pch_iir)
>  {
>  	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
>  	int pipe;
> +	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK;
>  
> -	if (pch_iir & SDE_HOTPLUG_MASK)
> +	if (hotplug_trigger) {
> +		hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_ibx);
>  		queue_work(dev_priv->wq, &dev_priv->hotplug_work);
> -
> +	}
>  	if (pch_iir & SDE_AUDIO_POWER_MASK)
>  		DRM_DEBUG_DRIVER("PCH audio power change on port %d\n",
>  				 (pch_iir & SDE_AUDIO_POWER_MASK) >>
> @@ -722,10 +754,12 @@ static void cpt_irq_handler(struct drm_device *dev, u32 pch_iir)
>  {
>  	drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
>  	int pipe;
> +	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK_CPT;
>  
> -	if (pch_iir & SDE_HOTPLUG_MASK_CPT)
> +	if (hotplug_trigger) {
> +		hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_cpt);
>  		queue_work(dev_priv->wq, &dev_priv->hotplug_work);
> -
> +	}
>  	if (pch_iir & SDE_AUDIO_POWER_MASK_CPT)
>  		DRM_DEBUG_DRIVER("PCH audio power change on port %d\n",
>  				 (pch_iir & SDE_AUDIO_POWER_MASK_CPT) >>
> @@ -2468,13 +2502,15 @@ static irqreturn_t i915_irq_handler(int irq, void *arg)
>  		if ((I915_HAS_HOTPLUG(dev)) &&
>  		    (iir & I915_DISPLAY_PORT_INTERRUPT)) {
>  			u32 hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
> +			u32 hotplug_trigger = hotplug_status & HOTPLUG_INT_STATUS_I915;
>  
>  			DRM_DEBUG_DRIVER("hotplug event received, stat 0x%08x\n",
>  				  hotplug_status);
> -			if (hotplug_status & HOTPLUG_INT_STATUS_I915)
> +			if (hotplug_trigger) {
> +				hotplug_irq_storm_detect(dev, hotplug_trigger, hpd_status_i915);
>  				queue_work(dev_priv->wq,
>  					   &dev_priv->hotplug_work);
> -
> +			}
>  			I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
>  			POSTING_READ(PORT_HOTPLUG_STAT);
>  		}
> @@ -2701,15 +2737,18 @@ static irqreturn_t i965_irq_handler(int irq, void *arg)
>  		/* Consume port.  Then clear IIR or we'll miss events */
>  		if (iir & I915_DISPLAY_PORT_INTERRUPT) {
>  			u32 hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
> +			u32 hotplug_trigger = hotplug_status & (IS_G4X(dev) ?
> +								  HOTPLUG_INT_STATUS_G4X :
> +								  HOTPLUG_INT_STATUS_I965);
>  
>  			DRM_DEBUG_DRIVER("hotplug event received, stat 0x%08x\n",
>  				  hotplug_status);
> -			if (hotplug_status & (IS_G4X(dev) ?
> -					      HOTPLUG_INT_STATUS_G4X :
> -					      HOTPLUG_INT_STATUS_I965))
> +			if (hotplug_trigger) {
> +				hotplug_irq_storm_detect(dev, hotplug_trigger,
> +							 IS_G4X(dev) ? hpd_status_gen4 : hpd_status_i965);
>  				queue_work(dev_priv->wq,
>  					   &dev_priv->hotplug_work);
> -
> +			}
>  			I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
>  			I915_READ(PORT_HOTPLUG_STAT);
>  		}
> -- 
> 1.7.7
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch


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