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Commit a4af7889 authored by Lyude Paul's avatar Lyude Paul
Browse files

drm/i915: Fix threshold check in intel_hpd_irq_storm_detect() 



Currently in intel_hpd_irq_storm_detect() when we detect that the last
recorded hotplug wasn't within the period defined by
HPD_STORM_DETECT_DELAY, we make the mistake of resetting the HPD count
to 0 without incrementing it. This results in us only enabling storm
detection when we go +2 above the threshold, e.g. an HPD threshold of 5
would not trigger a storm until we reach a total of 7 hotplugs.

So: rework the code a bit so we reset the HPD count when
HPD_STORM_DETECT_DELAY has passed, then increment the count afterwards.
Also, clean things up a bit to make it easier to undertand.

Signed-off-by: default avatarLyude Paul <lyude@redhat.com>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181106213017.14563-4-lyude@redhat.com
parent fee61dee

drivers/gpu/drm/i915/intel_hotplug.c

+13 −10
Original line number Diff line number Diff line
@@ -135,24 +135,27 @@ enum hpd_pin intel_hpd_pin_default(struct drm_i915_private *dev_priv, 
static bool intel_hpd_irq_storm_detect(struct drm_i915_private *dev_priv,

				       enum hpd_pin pin)

{

	unsigned long start = dev_priv->hotplug.stats[pin].last_jiffies;

	struct i915_hotplug *hpd = &dev_priv->hotplug;

	unsigned long start = hpd->stats[pin].last_jiffies;

	unsigned long end = start + msecs_to_jiffies(HPD_STORM_DETECT_PERIOD);

	const int threshold = dev_priv->hotplug.hpd_storm_threshold;

	const int threshold = hpd->hpd_storm_threshold;

	bool storm = false;



	if (!threshold)

		return false;



	if (!time_in_range(jiffies, start, end)) {

		dev_priv->hotplug.stats[pin].last_jiffies = jiffies;

		dev_priv->hotplug.stats[pin].count = 0;

		DRM_DEBUG_KMS("Received HPD interrupt on PIN %d - cnt: 0\n", pin);

	} else if (dev_priv->hotplug.stats[pin].count > threshold &&

		   threshold) {

		dev_priv->hotplug.stats[pin].state = HPD_MARK_DISABLED;

		hpd->stats[pin].last_jiffies = jiffies;

		hpd->stats[pin].count = 0;

	}



	if (++hpd->stats[pin].count > threshold) {

		hpd->stats[pin].state = HPD_MARK_DISABLED;

		DRM_DEBUG_KMS("HPD interrupt storm detected on PIN %d\n", pin);

		storm = true;

	} else {

		dev_priv->hotplug.stats[pin].count++;

		DRM_DEBUG_KMS("Received HPD interrupt on PIN %d - cnt: %d\n", pin,

			      dev_priv->hotplug.stats[pin].count);

			      hpd->stats[pin].count);

	}



	return storm;