+/* Workaround for i830 bug where pipe a must be enable to change control regs */
+static int
+i830_activate_pipe_a(struct drm_device *dev)
+{
+ drm_i915_private_t *dev_priv = dev->dev_private;
+ struct intel_crtc *crtc;
+ struct drm_crtc_helper_funcs *crtc_funcs;
+ struct drm_display_mode vesa_640x480 = {
+ DRM_MODE("640x480", DRM_MODE_TYPE_DRIVER, 25175, 640, 656,
+ 752, 800, 0, 480, 489, 492, 525, 0,
+ DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC)
+ }, *mode;
+
+ crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[0]);
+ if (crtc->dpms_mode == DRM_MODE_DPMS_ON)
+ return 0;
+
+ /* most i8xx have pipe a forced on, so don't trust dpms mode */
+ if (I915_READ(PIPEACONF) & PIPEACONF_ENABLE)
+ return 0;
+
+ crtc_funcs = crtc->base.helper_private;
+ if (crtc_funcs->dpms == NULL)
+ return 0;
+
+ DRM_DEBUG_DRIVER("Enabling pipe A in order to enable overlay\n");
+
+ mode = drm_mode_duplicate(dev, &vesa_640x480);
+ drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
+ if(!drm_crtc_helper_set_mode(&crtc->base, mode,
+ crtc->base.x, crtc->base.y,
+ crtc->base.fb))
+ return 0;
+
+ crtc_funcs->dpms(&crtc->base, DRM_MODE_DPMS_ON);
+ return 1;
+}
+
+static void
+i830_deactivate_pipe_a(struct drm_device *dev)
+{
+ drm_i915_private_t *dev_priv = dev->dev_private;
+ struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[0];
+ struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+
+ crtc_funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
+}
+