drm/i915: Replace vblank PM QoS with "Interrupt-Based AGPBUSY#"
I stumbled over this magic bit in the gen3 INSTPM:
Bit11 Interrupt-Based AGPBUSY# Enable:
‘0’ = Pending GMCH interrupts will not cause AGPBUSY# assertion.
‘1’ = Pending GMCH interrupts will cause AGPBUSY# assertion and hence
can cause the CPU to exit C3. There is no suppression of cacheable
writes.
Note that in either case in C3 the interrupts are not lost. They will be
forwarded to the ICH when the GMCH is out of C3.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@kernel.org
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 39d7cd3..188b497 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1353,7 +1353,12 @@
else
i915_enable_pipestat(dev_priv, pipe,
PIPE_VBLANK_INTERRUPT_ENABLE);
+
+ /* maintain vblank delivery even in deep C-states */
+ if (dev_priv->info->gen == 3)
+ I915_WRITE(INSTPM, INSTPM_AGPBUSY_DIS << 16);
spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
+
return 0;
}
@@ -1366,6 +1371,10 @@
unsigned long irqflags;
spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+ if (dev_priv->info->gen == 3)
+ I915_WRITE(INSTPM,
+ INSTPM_AGPBUSY_DIS << 16 | INSTPM_AGPBUSY_DIS);
+
if (HAS_PCH_SPLIT(dev))
ironlake_disable_display_irq(dev_priv, (pipe == 0) ?
DE_PIPEA_VBLANK: DE_PIPEB_VBLANK);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e1be98f..368819a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -405,9 +405,12 @@
#define I915_ERROR_INSTRUCTION (1<<0)
#define INSTPM 0x020c0
#define INSTPM_SELF_EN (1<<12) /* 915GM only */
+#define INSTPM_AGPBUSY_DIS (1<<11) /* gen3: when disabled, pending interrupts
+ will not assert AGPBUSY# and will only
+ be delivered when out of C3. */
#define ACTHD 0x020c8
#define FW_BLC 0x020d8
-#define FW_BLC2 0x020dc
+#define FW_BLC2 0x020dc
#define FW_BLC_SELF 0x020e0 /* 915+ only */
#define FW_BLC_SELF_EN_MASK (1<<31)
#define FW_BLC_SELF_FIFO_MASK (1<<16) /* 945 only */