diff mbox

[v2,2/2] drm/i915: Fix races in gen4 page flip interrupt handling

Message ID 1361279799-16582-3-git-send-email-ville.syrjala@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ville Syrjala Feb. 19, 2013, 1:16 p.m. UTC 
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Use the gen3 logic for handling page flip interrupts on gen4.

Unfortuantely this kills the stall_check since that looks like it can
easily trigger too early. With the current logic the stall check would
kick in on the first vblank after the flip has been submitted to the
ring. If the CS takes longer than that to process the commands in the
ring, the stall check will cause the page flip to be complete too
early. That doesn't sound like a very good idea. Something better
should be deviced if we still need the stall check. For now, mark
i915_pageflip_stall_check() as unused.

v2: Fix irq enable_mask and add __always_unused (Chris Wilson)

References: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1116587
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

Comments

Daniel Vetter Feb. 20, 2013, 2:38 p.m. UTC | #1 
On Tue, Feb 19, 2013 at 03:16:39PM +0200, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Use the gen3 logic for handling page flip interrupts on gen4.
> 
> Unfortuantely this kills the stall_check since that looks like it can
> easily trigger too early. With the current logic the stall check would
> kick in on the first vblank after the flip has been submitted to the
> ring. If the CS takes longer than that to process the commands in the
> ring, the stall check will cause the page flip to be complete too
> early. That doesn't sound like a very good idea. Something better
> should be deviced if we still need the stall check. For now, mark
> i915_pageflip_stall_check() as unused.
> 
> v2: Fix irq enable_mask and add __always_unused (Chris Wilson)
> 
> References: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1116587
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Both merge to dinq, thanks.
-Daniel
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 6488249..18de788 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1547,7 +1547,7 @@  void i915_handle_error(struct drm_device *dev, bool wedged)
 	queue_work(dev_priv->wq, &dev_priv->gpu_error.work);
 }
 
-static void i915_pageflip_stall_check(struct drm_device *dev, int pipe)
+static void __always_unused i915_pageflip_stall_check(struct drm_device *dev, int pipe)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
@@ -2598,6 +2598,8 @@  static int i965_irq_postinstall(struct drm_device *dev)
 			       I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT);
 
 	enable_mask = ~dev_priv->irq_mask;
+	enable_mask &= ~(I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT |
+			 I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT);
 	enable_mask |= I915_USER_INTERRUPT;
 
 	if (IS_G4X(dev))
@@ -2684,6 +2686,13 @@  static irqreturn_t i965_irq_handler(int irq, void *arg)
 	unsigned long irqflags;
 	int irq_received;
 	int ret = IRQ_NONE, pipe;
+	u32 flip[2] = {
+		I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT,
+		I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT
+	};
+	u32 flip_mask =
+		I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT |
+		I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT;
 
 	atomic_inc(&dev_priv->irq_received);
 
@@ -2692,7 +2701,7 @@  static irqreturn_t i965_irq_handler(int irq, void *arg)
 	for (;;) {
 		bool blc_event = false;
 
-		irq_received = iir != 0;
+		irq_received = (iir & ~flip_mask) != 0;
 
 		/* Can't rely on pipestat interrupt bit in iir as it might
 		 * have been cleared after the pipestat interrupt was received.
@@ -2739,7 +2748,7 @@  static irqreturn_t i965_irq_handler(int irq, void *arg)
 			I915_READ(PORT_HOTPLUG_STAT);
 		}
 
-		I915_WRITE(IIR, iir);
+		I915_WRITE(IIR, iir & ~flip_mask);
 		new_iir = I915_READ(IIR); /* Flush posted writes */
 
 		if (iir & I915_USER_INTERRUPT)
@@ -2747,17 +2756,17 @@  static irqreturn_t i965_irq_handler(int irq, void *arg)
 		if (iir & I915_BSD_USER_INTERRUPT)
 			notify_ring(dev, &dev_priv->ring[VCS]);
 
-		if (iir & I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT)
-			intel_prepare_page_flip(dev, 0);
-
-		if (iir & I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT)
-			intel_prepare_page_flip(dev, 1);
-
 		for_each_pipe(pipe) {
 			if (pipe_stats[pipe] & PIPE_START_VBLANK_INTERRUPT_STATUS &&
 			    drm_handle_vblank(dev, pipe)) {
-				i915_pageflip_stall_check(dev, pipe);
-				intel_finish_page_flip(dev, pipe);
+				if (iir & flip[pipe]) {
+					intel_prepare_page_flip(dev, pipe);
+
+					if ((I915_READ(ISR) & flip[pipe]) == 0) {
+						intel_finish_page_flip(dev, pipe);
+						flip_mask &= ~flip[pipe];
+					}
+				}
 			}
 
 			if (pipe_stats[pipe] & PIPE_LEGACY_BLC_EVENT_STATUS)