[PATCH] allow 945 to control self refresh automatically

[Alexander Lam <lambchop468@gmail.com>]

I changed 945's self refresh to work without the need for the driver to
enable/disable self refresh manually based on the idle state of the gpu.
This is much better than enabling/disabling self refresh for various
reasons, including staying in a lower power state for more time and
avoiding the need for cpu cycles.

Something must have been fixed in the driver between the initial
implementation of 945 self refresh and now.
(maybe 944001201ca0196bcdb088129e5866a9f379d08c: drm/i915: enable low
power render writes on GEN3 hardware?)

This patch probably doesn't cover all cases concerning if SR should
be enabled/disabled, not to mention doing things in the wrong order or
in the wrong place.

Signed-off-by: Alexander Lam <lambchop468@gmail.com>
Acked-by : Li Peng <peng.li@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |   37 ++++++++++-----------------------
 1 files changed, 11 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index fe56cb3..46f6878 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3316,7 +3316,7 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
 	int planea_wm, planeb_wm;
 	struct intel_watermark_params planea_params, planeb_params;
 	unsigned long line_time_us;
-	int sr_clock, sr_entries = 0;
+	int sr_clock, sr_entries = 0, sr_enabled = 0;
 
 	/* Create copies of the base settings for each pipe */
 	if (IS_CRESTLINE(dev) || IS_I945GM(dev))
@@ -3363,8 +3363,11 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
 		if (srwm < 0)
 			srwm = 1;
 
-		if (IS_I945G(dev) || IS_I945GM(dev))
+		if (IS_I945G(dev) || IS_I945GM(dev)){
 			I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_FIFO_MASK | (srwm & 0xff));
+			DRM_DEBUG_KMS("enable memory self refresh on 945\n");
+			sr_enabled = 1;
+		}
 		else if (IS_I915GM(dev)) {
 			/* 915M has a smaller SRWM field */
 			I915_WRITE(FW_BLC_SELF, srwm & 0x3f);
@@ -3373,6 +3376,8 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
 	} else {
 		/* Turn off self refresh if both pipes are enabled */
 		if (IS_I945G(dev) || IS_I945GM(dev)) {
+			DRM_DEBUG_KMS("disable memory self refresh on 945\n");
+			sr_enabled = 0;
 			I915_WRITE(FW_BLC_SELF, I915_READ(FW_BLC_SELF)
 				   & ~FW_BLC_SELF_EN);
 		} else if (IS_I915GM(dev)) {
@@ -3392,6 +3397,8 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
 
 	I915_WRITE(FW_BLC, fwater_lo);
 	I915_WRITE(FW_BLC2, fwater_hi);
+	if (sr_enabled)
+		I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN_MASK | FW_BLC_SELF_EN);
 }
 
 static void i830_update_wm(struct drm_device *dev, int planea_clock, int unused,
@@ -5125,7 +5132,6 @@ static void intel_idle_update(struct work_struct *work)
 	struct drm_device *dev = dev_priv->dev;
 	struct drm_crtc *crtc;
 	struct intel_crtc *intel_crtc;
-	int enabled = 0;
 
 	if (!i915_powersave)
 		return;
@@ -5139,16 +5145,11 @@ static void intel_idle_update(struct work_struct *work)
 		if (!crtc->fb)
 			continue;
 
-		enabled++;
 		intel_crtc = to_intel_crtc(crtc);
 		if (!intel_crtc->busy)
 			intel_decrease_pllclock(crtc);
 	}
 
-	if ((enabled == 1) && (IS_I945G(dev) || IS_I945GM(dev))) {
-		DRM_DEBUG_DRIVER("enable memory self refresh on 945\n");
-		I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN_MASK | FW_BLC_SELF_EN);
-	}
 
 	mutex_unlock(&dev->struct_mutex);
 }
@@ -5173,17 +5174,9 @@ void intel_mark_busy(struct drm_device *dev, struct drm_i915_gem_object *obj)
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
 		return;
 
-	if (!dev_priv->busy) {
-		if (IS_I945G(dev) || IS_I945GM(dev)) {
-			u32 fw_blc_self;
-
-			DRM_DEBUG_DRIVER("disable memory self refresh on 945\n");
-			fw_blc_self = I915_READ(FW_BLC_SELF);
-			fw_blc_self &= ~FW_BLC_SELF_EN;
-			I915_WRITE(FW_BLC_SELF, fw_blc_self | FW_BLC_SELF_EN_MASK);
-		}
+	if (!dev_priv->busy)
 		dev_priv->busy = true;
-	} else
+	else
 		mod_timer(&dev_priv->idle_timer, jiffies +
 			  msecs_to_jiffies(GPU_IDLE_TIMEOUT));
 
@@ -5195,14 +5188,6 @@ void intel_mark_busy(struct drm_device *dev, struct drm_i915_gem_object *obj)
 		intel_fb = to_intel_framebuffer(crtc->fb);
 		if (intel_fb->obj == obj) {
 			if (!intel_crtc->busy) {
-				if (IS_I945G(dev) || IS_I945GM(dev)) {
-					u32 fw_blc_self;
-
-					DRM_DEBUG_DRIVER("disable memory self refresh on 945\n");
-					fw_blc_self = I915_READ(FW_BLC_SELF);
-					fw_blc_self &= ~FW_BLC_SELF_EN;
-					I915_WRITE(FW_BLC_SELF, fw_blc_self | FW_BLC_SELF_EN_MASK);
-				}
 				/* Non-busy -> busy, upclock */
 				intel_increase_pllclock(crtc);
 				intel_crtc->busy = true;
-- 
1.7.3.4