drm/i915/dsi: Remove readback of panel orientation on BYT / CHT

Commit 82daca2 ("drm/i915: Add "panel orientation" property to the
panel connector, v6.") uses hardware state readback to determine if the
GOP is rotating the image by 180 degrees to compensate for upside-down
mounted panels.

When I wrote that commit I tried to find the VBT bits the GOP used to
decide to rotate the image, but I could not find them. Back then I only
looked at the rotation bits in struct mipi_config and these read 0 on
the 1 BYT device I have with an upside-down mounted panel
(a GP-electronic T701 tablet). While working on a similar problem on a
BYT device with an eDP panel I noticed that the new
intel_dsi_get_panel_orientation() helper which gets used on newer
SoCs (Apollo-Lake, etc.) checks the rotate_180 bit in the
BDB_GENERAL_FEATURES VBT block.

I've checked and this bit indeed is set on the GP-electronic T701 tablet,
so using the generic intel_dsi_get_panel_orientation() helper there does
the right thing without needing any extra readback of hw state.

This commit removes the special handling of the panel orientation for
DSI panels on BYT/CHT devices, bringing the handling in line with the
handling of DSI panels on other devices.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228114110.187792-2-hdegoede@redhat.com

drivers/gpu/drm/i915/display/vlv_dsi.c

@@ -1591,59 +1591,6 @@ static const struct drm_connector_funcs intel_dsi_connector_funcs = {
 	.atomic_duplicate_state = intel_digital_connector_duplicate_state,
 };
 
-static enum drm_panel_orientation
-vlv_dsi_get_hw_panel_orientation(struct intel_connector *connector)
-{
-	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
-	struct intel_encoder *encoder = intel_attached_encoder(connector);
-	enum intel_display_power_domain power_domain;
-	enum drm_panel_orientation orientation;
-	struct intel_plane *plane;
-	struct intel_crtc *crtc;
-	intel_wakeref_t wakeref;
-	enum pipe pipe;
-	u32 val;
-
-	if (!encoder->get_hw_state(encoder, &pipe))
-		return DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
-
-	crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
-	plane = to_intel_plane(crtc->base.primary);
-
-	power_domain = POWER_DOMAIN_PIPE(pipe);
-	wakeref = intel_display_power_get_if_enabled(dev_priv, power_domain);
-	if (!wakeref)
-		return DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
-
-	val = intel_de_read(dev_priv, DSPCNTR(plane->i9xx_plane));
-
-	if (!(val & DISPLAY_PLANE_ENABLE))
-		orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
-	else if (val & DISPPLANE_ROTATE_180)
-		orientation = DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP;
-	else
-		orientation = DRM_MODE_PANEL_ORIENTATION_NORMAL;
-
-	intel_display_power_put(dev_priv, power_domain, wakeref);
-
-	return orientation;
-}
-
-static enum drm_panel_orientation
-vlv_dsi_get_panel_orientation(struct intel_connector *connector)
-{
-	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
-	enum drm_panel_orientation orientation;
-
-	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
-		orientation = vlv_dsi_get_hw_panel_orientation(connector);
-		if (orientation != DRM_MODE_PANEL_ORIENTATION_UNKNOWN)
-			return orientation;
-	}
-
-	return intel_dsi_get_panel_orientation(connector);
-}
-
 static void vlv_dsi_add_properties(struct intel_connector *connector)
 {
 	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
@@ -1662,7 +1609,7 @@ static void vlv_dsi_add_properties(struct intel_connector *connector)
 
 		drm_connector_set_panel_orientation_with_quirk(
 				&connector->base,
-				vlv_dsi_get_panel_orientation(connector),
+				intel_dsi_get_panel_orientation(connector),
 				connector->panel.fixed_mode->hdisplay,
 				connector->panel.fixed_mode->vdisplay);
 	}