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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: Lyude Paul <lyude@redhat.com>
Reviewed-by: Ville 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
This commit is contained in:
Lyude Paul 2018-11-06 16:30:14 -05:00
parent fee61deecb
commit a4af7889eb
1 changed files with 13 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/gpu/drm/i915/intel_hotplug.c
View File

@ -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;