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[10/17] drm/i915: Gen3 HWSTAM is actually 32 bits

Message ID 20170622115555.12176-11-ville.syrjala@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ville Syrjälä June 22, 2017, 11:55 a.m. UTC 
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Bspec claims that HWSTAM is only 16 bits on gen3, but the other
interrupts registers are 32 bits and there are 18 valid interrupt
bits. Hence a 16 bit HWSTAM wouldn't be able to contain all the
bits, so it seems the spec is incorrect about the size of the
register. And indeed I can clear bits 16 and 17 just fine with
a 32 bit write. So let's adjust the code to treat the register
as 32 bits.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Chris Wilson June 22, 2017, 12:45 p.m. UTC | #1 
Quoting ville.syrjala@linux.intel.com (2017-06-22 12:55:48)
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Bspec claims that HWSTAM is only 16 bits on gen3, but the other
> interrupts registers are 32 bits and there are 18 valid interrupt
> bits. Hence a 16 bit HWSTAM wouldn't be able to contain all the
> bits, so it seems the spec is incorrect about the size of the
> register. And indeed I can clear bits 16 and 17 just fine with
> a 32 bit write. So let's adjust the code to treat the register
> as 32 bits.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index b4c9a6a7023a..2b8aeb79a7a8 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -3793,7 +3793,7 @@  static void i915_irq_preinstall(struct drm_device * dev)
 
 	i9xx_pipestat_irq_reset(dev_priv);
 
-	I915_WRITE16(HWSTAM, 0xeffe);
+	I915_WRITE(HWSTAM, 0xffffeffe);
 
 	GEN3_IRQ_RESET();
 }
@@ -3989,7 +3989,7 @@  static void i915_irq_uninstall(struct drm_device * dev)
 
 	i9xx_pipestat_irq_reset(dev_priv);
 
-	I915_WRITE16(HWSTAM, 0xffff);
+	I915_WRITE(HWSTAM, 0xffffffff);
 
 	GEN3_IRQ_RESET();
 }