| Message ID | 1371037046-3732-9-git-send-email-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Daniel Vetter writes: > Our interrupt handler (in hardird context) could race with the timer Nitpick: s/d/q/ > (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). > > Cc: Egbert Eich <eich@suse.de> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> > --- > drivers/gpu/drm/i915/i915_irq.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c > index 1815891..95e15cd 100644 > --- a/drivers/gpu/drm/i915/i915_irq.c > +++ b/drivers/gpu/drm/i915/i915_irq.c > @@ -880,15 +880,13 @@ 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) || > @@ -911,10 +909,9 @@ 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); > @@ -3327,6 +3324,8 @@ 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; Didn't you want to do the same for ibx_hpd_irq_setup() ? > @@ -3610,6 +3609,7 @@ 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++) { > @@ -3622,6 +3622,11 @@ 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; > } > + > + /* Interrup setup is already guaranteed to be single-threaded, this is Nitpick - missed a 't'. > + * 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); > } > -- > 1.8.1.4
On Wed, Jun 12, 2013 at 4:59 PM, Egbert Eich <eich@suse.com> wrote: > > + 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; > > > Didn't you want to do the same for ibx_hpd_irq_setup() ? Will happen in a follow-up patch, since I first consolidate all access to SDEIMR into one single helper function. I've tried to explain that a bit in the commit message but failed to make the connection to ibx_hpd_irq_setup - once we have the helper function the assert_spin_locked is in there and so ibx_hpd_irq_setup doesn't need its own check (since it won't touch SDEIMR directly any more). -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 1815891..95e15cd 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -880,15 +880,13 @@ 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) || @@ -911,10 +909,9 @@ 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); @@ -3327,6 +3324,8 @@ 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; @@ -3610,6 +3609,7 @@ 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++) { @@ -3622,6 +3622,11 @@ 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; } + + /* Interrup 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); }
Our interrupt handler (in hardird 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). Cc: Egbert Eich <eich@suse.de> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/i915/i915_irq.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)