2018-11-21 01:20:08

by Lyude Paul

Subject: [PATCH] drm/i915: Synchronize hpd work in i915_hpd_storm_ctl_show()

While trying to add a chamelium test for short HPD IRQs, I ran into
issues where a hotplug storm would be triggered, but the point at which
it would be reported by the kernel would be after igt actually finished
checking i915_hpd_storm_ctl's status. So, fix this by simply
synchronizing our IRQ work, dig_port_work, and hotplug_work before
printing out the HPD storm status in i915_hpd_storm_ctl_show().

Signed-off-by: Lyude Paul <[email protected]>
Cc: Ville Syrjälä <[email protected]>
---
drivers/gpu/drm/i915/i915_debugfs.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 69447c68b9af..af4268a6d2d9 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4592,6 +4592,13 @@ static int i915_hpd_storm_ctl_show(struct seq_file *m, void *data)
struct drm_i915_private *dev_priv = m->private;
struct i915_hotplug *hotplug = &dev_priv->hotplug;

+ /* Synchronize with everything first in case there's been an HPD
+ * storm, but we haven't finished handling it in the kernel yet
+ */
+ synchronize_irq(dev_priv->drm.irq);
+ flush_work(&dev_priv->hotplug.dig_port_work);
+ flush_work(&dev_priv->hotplug.hotplug_work);
+
seq_printf(m, "Threshold: %d\n", hotplug->hpd_storm_threshold);
seq_printf(m, "Detected: %s\n",
yesno(delayed_work_pending(&hotplug->reenable_work)));
--
2.19.1

2018-11-21 11:17:48

by Daniel Vetter

Subject: Re: [PATCH] drm/i915: Synchronize hpd work in i915_hpd_storm_ctl_show()

On Tue, Nov 20, 2018 at 07:37:17PM -0500, Lyude Paul wrote:
> While trying to add a chamelium test for short HPD IRQs, I ran into
> issues where a hotplug storm would be triggered, but the point at which
> it would be reported by the kernel would be after igt actually finished
> checking i915_hpd_storm_ctl's status. So, fix this by simply
> synchronizing our IRQ work, dig_port_work, and hotplug_work before
> printing out the HPD storm status in i915_hpd_storm_ctl_show().
>
> Signed-off-by: Lyude Paul <[email protected]>
> Cc: Ville Syrj?l? <[email protected]>

Makes sense.

Reviewed-by: Daniel Vetter <[email protected]>

> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 69447c68b9af..af4268a6d2d9 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4592,6 +4592,13 @@ static int i915_hpd_storm_ctl_show(struct seq_file *m, void *data)
> struct drm_i915_private *dev_priv = m->private;
> struct i915_hotplug *hotplug = &dev_priv->hotplug;
>
> + /* Synchronize with everything first in case there's been an HPD
> + * storm, but we haven't finished handling it in the kernel yet
> + */
> + synchronize_irq(dev_priv->drm.irq);
> + flush_work(&dev_priv->hotplug.dig_port_work);
> + flush_work(&dev_priv->hotplug.hotplug_work);
> +
> seq_printf(m, "Threshold: %d\n", hotplug->hpd_storm_threshold);
> seq_printf(m, "Detected: %s\n",
> yesno(delayed_work_pending(&hotplug->reenable_work)));
> --
> 2.19.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch