[Intel-gfx] [PATCH] drm/i915: abstract hpd irq storm detection

[Paulo Zanoni]

2015-05-29 10:14 GMT-03:00 Jani Nikula <jani.nikula at intel.com>:
> Simplify intel_hpd_irq_handler() by extracting HPD irq storm detection
> to a separate function.

Much better!

I'd probably add a verb to the function name, and try to do something
to remove the debug messages from the "if" statement.

Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 53 +++++++++++++++++++++++++++++++----------
>  1 file changed, 40 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index e4260b0924f1..eb52a039d628 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1375,6 +1375,45 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_i915_private *dev_priv,
>  #define HPD_STORM_DETECT_PERIOD 1000
>  #define HPD_STORM_THRESHOLD 5
>
> +/**
> + * intel_hpd_irq_storm - gather stats and detect HPD irq storm on a pin
> + * @dev_priv: private driver data pointer
> + * @pin: the pin to gather stats on
> + *
> + * Gather stats about HPD irqs from the specified @pin, and detect irq
> + * storms. Only the pin specific stats and state are changed, the caller is
> + * responsible for further action.
> + *
> + * @HPD_STORM_THRESHOLD irqs are allowed within @HPD_STORM_DETECT_PERIOD ms,
> + * otherwise it's considered an irq storm, and the irq state is set to
> + * @HPD_MARK_DISABLED.
> + *
> + * Return true if an irq storm was detected on @pin.
> + */
> +static bool intel_hpd_irq_storm(struct drm_i915_private *dev_priv,
> +                               enum hpd_pin pin)
> +{
> +       unsigned long start = dev_priv->hotplug.stats[pin].last_jiffies;
> +       unsigned long end = start + msecs_to_jiffies(HPD_STORM_DETECT_PERIOD);
> +       bool storm = 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 > HPD_STORM_THRESHOLD) {
> +               dev_priv->hotplug.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);
> +       }
> +
> +       return storm;
> +}
> +
>  static bool pch_port_hotplug_long_detect(enum port port, u32 val)
>  {
>         switch (port) {
> @@ -1544,21 +1583,9 @@ static void intel_hpd_irq_handler(struct drm_device *dev,
>                         queue_hp = true;
>                 }
>
> -               if (!time_in_range(jiffies, dev_priv->hotplug.stats[i].last_jiffies,
> -                                  dev_priv->hotplug.stats[i].last_jiffies
> -                                  + msecs_to_jiffies(HPD_STORM_DETECT_PERIOD))) {
> -                       dev_priv->hotplug.stats[i].last_jiffies = jiffies;
> -                       dev_priv->hotplug.stats[i].count = 0;
> -                       DRM_DEBUG_KMS("Received HPD interrupt on PIN %d - cnt: 0\n", i);
> -               } else if (dev_priv->hotplug.stats[i].count > HPD_STORM_THRESHOLD) {
> -                       dev_priv->hotplug.stats[i].state = HPD_MARK_DISABLED;
> +               if (intel_hpd_irq_storm(dev_priv, i)) {
>                         dev_priv->hotplug.event_bits &= ~BIT(i);
> -                       DRM_DEBUG_KMS("HPD interrupt storm detected on PIN %d\n", i);
>                         storm_detected = true;
> -               } else {
> -                       dev_priv->hotplug.stats[i].count++;
> -                       DRM_DEBUG_KMS("Received HPD interrupt on PIN %d - cnt: %d\n", i,
> -                                     dev_priv->hotplug.stats[i].count);
>                 }
>         }
>
> --
> 2.1.4
>
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-- 
Paulo Zanoni