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drm/i915: fix hpd interrupt register locking

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Our interrupt handler (in hardirq context) could race with the timer
(in softirq context), hence we need to hold the spinlock around the
call to ->hdp_irq_setup in intel_hpd_irq_handler, too.

But as an optimization (and more so to clarify things) we don't need
to do the irqsave/restore dance in the hardirq context.

Note also that on ilk+ the race isn't just against the hotplug
reenable timer, but also against the fifo underrun reporting. That one
also modifies the SDEIMR register (again protected by the same
dev_priv->irq_lock).

To lock things down again sprinkle a assert_spin_locked. But exclude
the functions touching SDEIMR for now, I want to extract them all into
a new helper function (like we do already for pipestate, display
interrupts and all the various gt interrupts).

v2: Add the missing 't' Egbert spotted in a comment.

v3: Actually fix the right misspelled comment (Paulo).

Cc: Egbert Eich <eich@suse.de>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2013-06-27 17:52:15 +02:00
parent 91d131d21e
commit b5ea2d5681
1 changed files with 10 additions and 5 deletions
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15
drivers/gpu/drm/i915/i915_irq.c
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@ -877,15 +877,13 @@ static inline void intel_hpd_irq_handler(struct drm_device *dev,
const u32 *hpd)
{
drm_i915_private_t *dev_priv = dev->dev_private;
unsigned long irqflags;
int i;
bool storm_detected = false;
if (!hotplug_trigger)
return;
spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
spin_lock(&dev_priv->irq_lock);
for (i = 1; i < HPD_NUM_PINS; i++) {
if (!(hpd[i] & hotplug_trigger) ||
@ -908,10 +906,9 @@ static inline void intel_hpd_irq_handler(struct drm_device *dev,
}
}
spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
if (storm_detected)
dev_priv->display.hpd_irq_setup(dev);
spin_unlock(&dev_priv->irq_lock);
queue_work(dev_priv->wq,
&dev_priv->hotplug_work);
@ -3380,6 +3377,8 @@ static void i915_hpd_irq_setup(struct drm_device *dev)
struct intel_encoder *intel_encoder;
u32 hotplug_en;
assert_spin_locked(&dev_priv->irq_lock);
if (I915_HAS_HOTPLUG(dev)) {
hotplug_en = I915_READ(PORT_HOTPLUG_EN);
hotplug_en &= ~HOTPLUG_INT_EN_MASK;
@ -3663,6 +3662,7 @@ void intel_hpd_init(struct drm_device *dev)
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_mode_config *mode_config = &dev->mode_config;
struct drm_connector *connector;
unsigned long irqflags;
int i;
for (i = 1; i < HPD_NUM_PINS; i++) {
@ -3675,6 +3675,11 @@ void intel_hpd_init(struct drm_device *dev)
if (!connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
connector->polled = DRM_CONNECTOR_POLL_HPD;
}
/* Interrupt setup is already guaranteed to be single-threaded, this is
* just to make the assert_spin_locked checks happy. */
spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
if (dev_priv->display.hpd_irq_setup)
dev_priv->display.hpd_irq_setup(dev);
spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
}