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Commit 95736720 authored by Chris Wilson's avatar Chris Wilson Committed by Keith Packard
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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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarBen Widawsky <ben@bwidawsk.net>
Signed-off-by: default avatarKeith Packard <keithp@keithp.com>
parent f5a3d0c4

drivers/gpu/drm/i915/i915_drv.c

+10 −5
Original line number Diff line number Diff line
@@ -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)

{

	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 < 20 && loop--) {

		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)

drivers/gpu/drm/i915/i915_drv.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

drivers/gpu/drm/i915/i915_reg.h

+1 −0
Original line number Diff line number Diff line
@@ -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)