drm/i915: allow 945 to control self refresh (CxSR) automatically

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.

This was originally done manually to workaround issues with the hardware
hanging. However, since 944001201: drm/i915: enable low power render
writes on GEN3 hardware, automatic CxSR seems stable.

Signed-off-by: Alexander Lam <lambchop468@gmail.com>
Acked-by : Li Peng <peng.li@linux.intel.com>
[ickle: play safe with the ordering and disable CxSR before tweaking any
watermark and enable afterwards.]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 24 insertions, 38 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 36f9e97f05c4..fe8454a48eab 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3761,7 +3761,7 @@ 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))
@@ -3790,6 +3790,12 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
          */
         cwm = 2;
 
+        /* Play safe and disable self-refresh before adjusting watermarks. */
+        if (IS_I945G(dev) || IS_I945GM(dev))
+                I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN_MASK | 0);
+        else if (IS_I915GM(dev))
+                I915_WRITE(INSTPM, I915_READ(INSTPM) & ~INSTPM_SELF_EN);
+
         /* Calc sr entries for one plane configs */
         if (HAS_FW_BLC(dev) && sr_hdisplay &&
             (!planea_clock || !planeb_clock)) {
@@ -3809,20 +3815,12 @@ static void i9xx_update_wm(struct drm_device *dev, int planea_clock,
                         srwm = 1;
 
                 if (IS_I945G(dev) || IS_I945GM(dev))
-                        I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_FIFO_MASK | (srwm & 0xff));
-                else if (IS_I915GM(dev)) {
-                        /* 915M has a smaller SRWM field */
+                        I915_WRITE(FW_BLC_SELF,
+                                   FW_BLC_SELF_FIFO_MASK | (srwm & 0xff));
+                else if (IS_I915GM(dev))
                         I915_WRITE(FW_BLC_SELF, srwm & 0x3f);
-                        I915_WRITE(INSTPM, I915_READ(INSTPM) | INSTPM_SELF_EN);
-                }
-        } else {
-                /* Turn off self refresh if both pipes are enabled */
-                if (IS_I945G(dev) || IS_I945GM(dev)) {
-                        I915_WRITE(FW_BLC_SELF, I915_READ(FW_BLC_SELF)
-                                   & ~FW_BLC_SELF_EN);
-                } else if (IS_I915GM(dev)) {
-                        I915_WRITE(INSTPM, I915_READ(INSTPM) & ~INSTPM_SELF_EN);
-                }
+
+                sr_enabled = 1;
         }
 
         DRM_DEBUG_KMS("Setting FIFO watermarks - A: %d, B: %d, C: %d, SR %d\n",
@@ -3837,6 +3835,16 @@ 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) {
+                if (IS_I945G(dev) || IS_I945GM(dev))
+                        I915_WRITE(FW_BLC_SELF,
+                                   FW_BLC_SELF_EN_MASK | FW_BLC_SELF_EN);
+                else if (IS_I915GM(dev))
+                        I915_WRITE(INSTPM, I915_READ(INSTPM) | INSTPM_SELF_EN);
+                DRM_DEBUG_KMS("memory self refresh enabled\n");
+        } else
+                DRM_DEBUG_KMS("memory self refresh disabled\n");
 }
 
 static void i830_update_wm(struct drm_device *dev, int planea_clock, int unused,
@@ -5586,7 +5594,6 @@ 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;
@@ -5600,16 +5607,11 @@ 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);
 }
@@ -5634,17 +5636,9 @@ 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));
 
@@ -5656,14 +5650,6 @@ 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;