drm/i915: save/restore fence registers across suspend/resume

This makes software fallbacks not do tiling wrong on i965 and later after
resume. It also should fix 945 performance reduction after resume which
would have disabled tiling without causing any visible effect.
Signed-off-by: Keith Packard <keithp@keithp.com>
[anholt: Fixed up the 915 case to not save/restore the new regs]
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_drv.h

@@ -283,6 +283,7 @@ typedef struct drm_i915_private {
 	u8 saveAR[21];
 	u8 saveDACMASK;
 	u8 saveCR[37];
+	uint64_t saveFENCE[16];
 
 	struct {
 		struct drm_mm gtt_space;

drivers/gpu/drm/i915/i915_suspend.c

@@ -349,6 +349,18 @@ int i915_save_state(struct drm_device *dev)
 	for (i = 0; i < 3; i++)
 		dev_priv->saveSWF2[i] = I915_READ(SWF30 + (i << 2));
 
+	/* Fences */
+	if (IS_I965G(dev)) {
+		for (i = 0; i < 16; i++)
+			dev_priv->saveFENCE[i] = I915_READ64(FENCE_REG_965_0 + (i * 8));
+	} else {
+		for (i = 0; i < 8; i++)
+			dev_priv->saveFENCE[i] = I915_READ(FENCE_REG_830_0 + (i * 4));
+
+		if (IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
+			for (i = 0; i < 8; i++)
+				dev_priv->saveFENCE[i+8] = I915_READ(FENCE_REG_945_8 + (i * 4));
+	}
 	i915_save_vga(dev);
 
 	return 0;
@@ -371,6 +383,18 @@ int i915_restore_state(struct drm_device *dev)
 	/* Display arbitration */
 	I915_WRITE(DSPARB, dev_priv->saveDSPARB);
 
+	/* Fences */
+	if (IS_I965G(dev)) {
+		for (i = 0; i < 16; i++)
+			I915_WRITE64(FENCE_REG_965_0 + (i * 8), dev_priv->saveFENCE[i]);
+	} else {
+		for (i = 0; i < 8; i++)
+			I915_WRITE(FENCE_REG_830_0 + (i * 4), dev_priv->saveFENCE[i]);
+		if (IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev))
+			for (i = 0; i < 8; i++)
+				I915_WRITE(FENCE_REG_945_8 + (i * 4), dev_priv->saveFENCE[i+8]);
+	}
+
 	/* Pipe & plane A info */
 	/* Prime the clock */
 	if (dev_priv->saveDPLL_A & DPLL_VCO_ENABLE) {