[Intel-gfx] 945 with SR doesn't need manual enable/disable

[Alexander Lam]

Hi all,

Using 2.6.35.2, 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.

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?)

patch (which 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):

diff -uNrp a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
--- a/drivers/gpu/drm/i915/intel_display.c      2010-08-01
18:11:14.000000000 -0400
+++ b/drivers/gpu/drm/i915/intel_display.c      2010-08-22
16:52:24.168999994 -0400
@@ -3016,7 +3016,7 @@ static void i9xx_update_wm(struct drm_de
       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_I965GM(dev) || IS_I945GM(dev))
@@ -3063,8 +3063,11 @@ static void i9xx_update_wm(struct drm_de
               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_DRIVER("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);
@@ -3073,6 +3076,8 @@ static void i9xx_update_wm(struct drm_de
       } else {
               /* Turn off self refresh if both pipes are enabled */
               if (IS_I945G(dev) || IS_I945GM(dev)) {
+                       DRM_DEBUG_DRIVER("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)) {
@@ -3092,6 +3097,8 @@ static void i9xx_update_wm(struct drm_de

       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,
@@ -4506,7 +4513,6 @@ static void intel_idle_update(struct wor
       struct drm_device *dev = dev_priv->dev;
       struct drm_crtc *crtc;
       struct intel_crtc *intel_crtc;
-       int enabled = 0;

       if (!i915_powersave)
               return;
@@ -4520,16 +4526,11 @@ static void intel_idle_update(struct wor
               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);
 }
@@ -4554,17 +4555,9 @@ void intel_mark_busy(struct drm_device *
       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));

@@ -4576,14 +4569,6 @@ void intel_mark_busy(struct drm_device *
               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, true);
                               intel_crtc->busy = true;


--
Alexander Lam