drm/i915: Handle PendingFlip on gen3 robustly

We appear to allow too many pending pageflips as evidenced by an
apparent pin-leak. So borrow the pageflip completion logic from i8xx for
handling PendingFlip in a robust manner.

v2: Address Jesse's reminders about the nuances of gen3 IRQ handling.

References: https://bugzilla.kernel.org/show_bug.cgi?id=41882
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 24d23a2..51f8720 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2350,16 +2350,31 @@ static void i915_irq_preinstall(struct drm_device * dev)
 static int i915_irq_postinstall(struct drm_device *dev)
 {
        drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
-       u32 enable_mask = I915_INTERRUPT_ENABLE_FIX | I915_INTERRUPT_ENABLE_VAR;
+       u32 enable_mask;
 
        dev_priv->vblank_pipe = DRM_I915_VBLANK_PIPE_A | DRM_I915_VBLANK_PIPE_B;
 
-       /* Unmask the interrupts that we always want on. */
-       dev_priv->irq_mask = ~I915_INTERRUPT_ENABLE_FIX;
-
        dev_priv->pipestat[0] = 0;
        dev_priv->pipestat[1] = 0;
 
+       I915_WRITE(EMR, ~(I915_ERROR_PAGE_TABLE | I915_ERROR_MEMORY_REFRESH));
+
+       /* Unmask the interrupts that we always want on. */
+       dev_priv->irq_mask =
+               ~(I915_ASLE_INTERRUPT |
+                 I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
+                 I915_DISPLAY_PIPE_B_EVENT_INTERRUPT |
+                 I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT |
+                 I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT |
+                 I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT);
+
+       enable_mask =
+               I915_ASLE_INTERRUPT |
+               I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
+               I915_DISPLAY_PIPE_B_EVENT_INTERRUPT |
+               I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT |
+               I915_USER_INTERRUPT;
+
        if (I915_HAS_HOTPLUG(dev)) {
                /* Enable in IER... */
                enable_mask |= I915_DISPLAY_PORT_INTERRUPT;
@@ -2367,12 +2382,6 @@ static int i915_irq_postinstall(struct drm_device *dev)
                dev_priv->irq_mask &= ~I915_DISPLAY_PORT_INTERRUPT;
        }
 
-       /*
-        * Enable some error detection, note the instruction error mask
-        * bit is reserved, so we leave it masked.
-        */
-       I915_WRITE(EMR, ~(I915_ERROR_PAGE_TABLE | I915_ERROR_MEMORY_REFRESH));
-
        I915_WRITE(IMR, dev_priv->irq_mask);
        I915_WRITE(IER, enable_mask);
        POSTING_READ(IER);
@@ -2412,15 +2421,21 @@ static irqreturn_t i915_irq_handler(DRM_IRQ_ARGS)
        struct drm_i915_master_private *master_priv;
        u32 iir, new_iir, pipe_stats[I915_MAX_PIPES];
        unsigned long irqflags;
-       int ret = IRQ_NONE, pipe;
+       u32 flip_mask =
+               I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT |
+               I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT;
+       u32 flip[2] = {
+               I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT,
+               I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT
+       };
+       int pipe, ret = IRQ_NONE;
 
        atomic_inc(&dev_priv->irq_received);
 
        iir = I915_READ(IIR);
-
-       for (;;) {
+       do {
+               bool irq_received = (iir & ~flip_mask) != 0;
                bool blc_event = false;
-               int irq_received = iir != 0;
 
                /* Can't rely on pipestat interrupt bit in iir as it might
                 * have been cleared after the pipestat interrupt was received.
@@ -2435,15 +2450,13 @@ static irqreturn_t i915_irq_handler(DRM_IRQ_ARGS)
                        int reg = PIPESTAT(pipe);
                        pipe_stats[pipe] = I915_READ(reg);
 
-                       /*
-                        * Clear the PIPE*STAT regs before the IIR
-                        */
+                       /* Clear the PIPE*STAT regs before the IIR */
                        if (pipe_stats[pipe] & 0x8000ffff) {
                                if (pipe_stats[pipe] & PIPE_FIFO_UNDERRUN_STATUS)
                                        DRM_DEBUG_DRIVER("pipe %c underrun\n",
                                                         pipe_name(pipe));
                                I915_WRITE(reg, pipe_stats[pipe]);
-                               irq_received = 1;
+                               irq_received = true;
                        }
                }
                spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
@@ -2451,8 +2464,6 @@ static irqreturn_t i915_irq_handler(DRM_IRQ_ARGS)
                if (!irq_received)
                        break;
 
-               ret = IRQ_HANDLED;
-
                /* Consume port.  Then clear IIR or we'll miss events */
                if ((I915_HAS_HOTPLUG(dev)) &&
                    (iir & I915_DISPLAY_PORT_INTERRUPT)) {
@@ -2465,26 +2476,26 @@ static irqreturn_t i915_irq_handler(DRM_IRQ_ARGS)
                                           &dev_priv->hotplug_work);
 
                        I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
-                       I915_READ(PORT_HOTPLUG_STAT);
+                       POSTING_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)
                        notify_ring(dev, &dev_priv->ring[RCS]);
 
-               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) {
+                       int plane = pipe;
+                       if (IS_MOBILE(dev))
+                               plane = !plane;
                        if (pipe_stats[pipe] & PIPE_VBLANK_INTERRUPT_STATUS &&
                            drm_handle_vblank(dev, pipe)) {
-                               i915_pageflip_stall_check(dev, pipe);
-                               intel_finish_page_flip(dev, pipe);
+                               if (iir & flip[plane]) {
+                                       intel_prepare_page_flip(dev, plane);
+                                       intel_finish_page_flip(dev, pipe);
+                                       flip_mask &= ~flip[plane];
+                               }
                        }
 
                        if (pipe_stats[pipe] & PIPE_LEGACY_BLC_EVENT_STATUS)
@@ -2509,8 +2520,9 @@ static irqreturn_t i915_irq_handler(DRM_IRQ_ARGS)
                 * trigger the 99% of 100,000 interrupts test for disabling
                 * stray interrupts.
                 */
+               ret = IRQ_HANDLED;
                iir = new_iir;
-       }
+       } while (iir & ~flip_mask);
 
        if (dev->primary->master) {
                master_priv = dev->primary->master->driver_priv;