On Mon, Nov 05, 2018 at 05:20:09PM -0500, Lyude Paul wrote:
> 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.
>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Looks good to me
Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_hotplug.c | 23 +++++++++++++----------
> 1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index 8326900a311e..c11d73de16f2 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -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;
> --
> 2.19.1
--
Ville Syrjälä
Intel
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