drm/i915: Turn on 945 self-refresh only if single CRTC is active

Enable self-refresh on 945 when just one CRTC is activated.
Otherwise user would get display flicker with dual display.

This fixes https://bugs.freedesktop.org/show_bug.cgi?id=27667

Signed-off-by: Li Peng <peng.li@intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a8d65b7cb72a21ae9f0fc37b4dade629db203984..fdeff43537257b3b23570aa77b9a3268d2bae33d 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4483,6 +4483,7 @@ 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;
@@ -4491,21 +4492,22 @@ static void intel_idle_update(struct work_struct *work)
 
        i915_update_gfx_val(dev_priv);
 
-       if (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);
-       }
-
        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
                /* Skip inactive CRTCs */
                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);
 }