drm/i915: rip out the overlay pipe A workaround

Now that all affected i830M systems have the pipe A quirk set,
we don't need to do any special dances in the overlay code any
longer. And reading through the code I'm rather dubios that it
actually does what it claims to do ...

As a nice benefit this rips out a users of the crtc helper dpms
callback.

v2: As suggested by Chris Wilson, replace the code by an appropriate
WARN to ensure that the pipe A is indeed running.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_overlay.c

@@ -235,54 +235,6 @@ static int intel_overlay_do_wait_request(struct intel_overlay *overlay,
 	return 0;
 }
 
-/* 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) & PIPECONF_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);
-
-	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);
-}
-
 /* overlay needs to be disable in OCMD reg */
 static int intel_overlay_on(struct intel_overlay *overlay)
 {
@@ -290,17 +242,12 @@ static int intel_overlay_on(struct intel_overlay *overlay)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_ring_buffer *ring = &dev_priv->ring[RCS];
 	struct drm_i915_gem_request *request;
-	int pipe_a_quirk = 0;
 	int ret;
 
 	BUG_ON(overlay->active);
 	overlay->active = 1;
 
-	if (IS_I830(dev)) {
-		pipe_a_quirk = i830_activate_pipe_a(dev);
-		if (pipe_a_quirk < 0)
-			return pipe_a_quirk;
-	}
+	WARN_ON(IS_I830(dev) && !(dev_priv->quirks & QUIRK_PIPEA_FORCE));
 
 	request = kzalloc(sizeof(*request), GFP_KERNEL);
 	if (request == NULL) {
@@ -322,9 +269,6 @@ static int intel_overlay_on(struct intel_overlay *overlay)
 
 	ret = intel_overlay_do_wait_request(overlay, request, NULL);
 out:
-	if (pipe_a_quirk)
-		i830_deactivate_pipe_a(dev);
-
 	return ret;
 }