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authorChris Wilson <chris@chris-wilson.co.uk>2011-05-12 22:17:09 +0100
committerKeith Packard <keithp@keithp.com>2011-07-13 11:28:07 -0700
commit95736720fc866eadb2ce1789631b907c0f38cb7c (patch)
tree5071fe60b3cdd5951e351e1565121287aa17675a /drivers
parentf5a3d0c4086d1854cbda545092c462b84cba20ce (diff)
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drm/i915: Cache GT fifo count for SandyBridge
The read back of the available FIFO entries is vital for system stability, but extremely costly. However, we only need a guide so as to avoid eating into the reserved entries and since we are the only consumer we can cache the read of the count from the last write. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Keith Packard <keithp@keithp.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/i915/i915_drv.c15
-rw-r--r--drivers/gpu/drm/i915/i915_drv.h1
-rw-r--r--drivers/gpu/drm/i915/i915_reg.h1
3 files changed, 12 insertions, 5 deletions
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6ed73ae2133a..d988cc350f66 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -348,12 +348,17 @@ void gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
void __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
{
- int loop = 500;
- u32 fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES);
- while (fifo < 20 && loop--) {
- udelay(10);
- fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES);
+ if (dev_priv->gt_fifo_count < GT_FIFO_NUM_RESERVED_ENTRIES ) {
+ int loop = 500;
+ u32 fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES);
+ while (fifo <= GT_FIFO_NUM_RESERVED_ENTRIES && loop--) {
+ udelay(10);
+ fifo = I915_READ_NOTRACE(GT_FIFO_FREE_ENTRIES);
+ }
+ WARN_ON(loop < 0 && fifo <= GT_FIFO_NUM_RESERVED_ENTRIES);
+ dev_priv->gt_fifo_count = fifo;
}
+ dev_priv->gt_fifo_count--;
}
static int i915_drm_freeze(struct drm_device *dev)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 00dc59a51ccd..b37146c4526f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -277,6 +277,7 @@ typedef struct drm_i915_private {
int relative_constants_mode;
void __iomem *regs;
+ u32 gt_fifo_count;
struct intel_gmbus {
struct i2c_adapter adapter;
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 96fb0fa47c40..02db299f621a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3361,6 +3361,7 @@
#define FORCEWAKE_ACK 0x130090
#define GT_FIFO_FREE_ENTRIES 0x120008
+#define GT_FIFO_NUM_RESERVED_ENTRIES 20
#define GEN6_RPNSWREQ 0xA008
#define GEN6_TURBO_DISABLE (1<<31)