drm/i915: Some polish for the new pipestat_irq_handler

Just a bit of polish which I hope will help me with massaging some
internal patches to use Imre's reworked pipestat handling:
- Don't check for underrun reporting or enable pipestat interrupts
  twice.
- Frob the comments a bit.
- Do the iir PIPE_EVENT to pipe mapping explicitly with a switch. We
  only have one place which does this, so better to make it explicit.

v2: Ville noticed that I've broken the logic a bit with trying to
avoid checking whether we're interested in a given pipe twice. push
the PIPESTAT read down after we've computed the mask of interesting
bits first to avoid that duplication properly.

v3: Squash in fixups from Imre on irc.

Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
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 b2c5c2b..69f2ebb 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1560,25 +1560,40 @@ static void valleyview_pipestat_irq_handler(struct drm_device *dev, u32 iir)
        spin_lock(&dev_priv->irq_lock);
        for_each_pipe(pipe) {
                int reg;
-               u32 mask;
+               u32 mask, iir_bit = 0;
 
-               if (!dev_priv->pipestat_irq_mask[pipe] &&
-                   !__cpu_fifo_underrun_reporting_enabled(dev, pipe))
+               /*
+                * PIPESTAT bits get signalled even when the interrupt is
+                * disabled with the mask bits, and some of the status bits do
+                * not generate interrupts at all (like the underrun bit). Hence
+                * we need to be careful that we only handle what we want to
+                * handle.
+                */
+               mask = 0;
+               if (__cpu_fifo_underrun_reporting_enabled(dev, pipe))
+                       mask |= PIPE_FIFO_UNDERRUN_STATUS;
+
+               switch (pipe) {
+               case PIPE_A:
+                       iir_bit = I915_DISPLAY_PIPE_A_EVENT_INTERRUPT;
+                       break;
+               case PIPE_B:
+                       iir_bit = I915_DISPLAY_PIPE_B_EVENT_INTERRUPT;
+                       break;
+               }
+               if (iir & iir_bit)
+                       mask |= dev_priv->pipestat_irq_mask[pipe];
+
+               if (!mask)
                        continue;
 
                reg = PIPESTAT(pipe);
-               pipe_stats[pipe] = I915_READ(reg);
+               mask |= PIPESTAT_INT_ENABLE_MASK;
+               pipe_stats[pipe] = I915_READ(reg) & mask;
 
                /*
                 * Clear the PIPE*STAT regs before the IIR
                 */
-               mask = PIPESTAT_INT_ENABLE_MASK;
-               if (__cpu_fifo_underrun_reporting_enabled(dev, pipe))
-                       mask |= PIPE_FIFO_UNDERRUN_STATUS;
-               if (iir & I915_DISPLAY_PIPE_EVENT_INTERRUPT(pipe))
-                       mask |= dev_priv->pipestat_irq_mask[pipe];
-               pipe_stats[pipe] &= mask;
-
                if (pipe_stats[pipe] & (PIPE_FIFO_UNDERRUN_STATUS |
                                        PIPESTAT_INT_STATUS_MASK))
                        I915_WRITE(reg, pipe_stats[pipe]);

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index fc03142..3579a9c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -997,10 +997,6 @@
 #define I915_DISPLAY_PIPE_A_EVENT_INTERRUPT            (1<<6)
 #define I915_DISPLAY_PIPE_B_VBLANK_INTERRUPT           (1<<5)
 #define I915_DISPLAY_PIPE_B_EVENT_INTERRUPT            (1<<4)
-#define I915_DISPLAY_PIPE_EVENT_INTERRUPT(pipe)                                \
-       ((pipe) == PIPE_A ? I915_DISPLAY_PIPE_A_EVENT_INTERRUPT :       \
-        I915_DISPLAY_PIPE_B_EVENT_INTERRUPT)
-
 #define I915_DEBUG_INTERRUPT                           (1<<2)
 #define I915_USER_INTERRUPT                            (1<<1)
 #define I915_ASLE_INTERRUPT                            (1<<0)