On 6/29/2015 10:07 PM, Daniel Vetter wrote:
On Mon, Jun 29, 2015 at 04:30:40PM +0530, Sivakumar Thulasimani wrote:
From: "Thulasimani, Sivakumar" <sivakumar.thulasimani@xxxxxxxxx>
HPD storm is detected in intel_hpd_irq_handler and disabled for respective
port immediately but polling is enabled only in i915_hotplug_work_func and
not in i915_digport_work_func. This will result in disabled hpd never enabled
back again. This is fixed by calling the appropriate storm disable function
that will handle the rest of the sequence (both polling enable and reenabling
of HPD later).
---
drivers/gpu/drm/i915/intel_hotplug.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
index 3c53aac..8e18587 100644
--- a/drivers/gpu/drm/i915/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/intel_hotplug.c
@@ -205,6 +205,10 @@ static void i915_digport_work_func(struct work_struct *work)
dev_priv->hotplug.long_port_mask = 0;
short_port_mask = dev_priv->hotplug.short_port_mask;
dev_priv->hotplug.short_port_mask = 0;
+
+ /* Disable hotplug on connectors that hit an irq storm. */
+ intel_hpd_irq_storm_disable(dev_priv);
digport_work_func schedules the hotplug handler for everything not
handled, which should result in this getting called. It really shouldn't
matter when exactly it gets called.
Can you please provide more data and details for your analysis? Like bug
reports, backtraces and dmesg traces showing that the handler is stuck and
similar things.
Also your patch is missing the s-o-b line.
-Daniel
there is no bug filed for this, it was observed as part of code analysis
(that is provided below)
I'll try to get more info as soon as i get access to a system.
short answer:
the issue will be seen during hpd storm, where the last HPD is handled
inside intel_dp_hpd_pulse.
so i915_hotplug_work_func will not be queued thus missing the
storm_disable call.
long answer :
To give a bit more background, lets assume that we get a call to
intel_hpd_irq_handler, with params long pulse for DP panel in PORT_B
on a HSW/BDW system during HPD storm scenario.
The following sequence will take place
*) is_dig_port will be set and will result in queue_dig being set as well
*) intel_hpd_irq_storm_detect will detect that this is 6th hpd call
within the
HPD_STORM_DETECT_PERIOD and so will mark the HPD status of PORT_B to
HPD_MARK_DISABLED
*) This will result in HPD for PORT_B being disabled immediately(masked
in case of LPT)
*) i915_digport_work_func will be queued at the end of this function,
since queue_dig is set
*) once in the i915_digport_work_func, hpd_pulse func pointer will be
executed since it is defined for DP
*) intel_dp_hpd_pulse, will have long_hpd set and since the panel is
plugged in still,
ISR will be high and so will return true.
*) intel_dp_get_dpcd, will succeed since DP is connected
*) finally IRQ_HANDLED will be returned
*) once call exits intel_hpd_irq_handler, HPD on port B will never be
enabled again
(unmasked in case of LPT) and no more hot plug notifications.
sorry for the incomplete patch , i'll reupload again once i get some
more details.
spin_unlock_irq(&dev_priv->irq_lock);
for (i = 0; i < I915_MAX_PORTS; i++) {
--
1.7.9.5
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--
regards,
Sivakumar
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