drm/i915: Determine DSI panel orientation from VBT

VBT appears to have two (or possibly three) ways to indicate the panel
rotation. The first is in the MIPI config block, but that apparenly
usually (maybe always?) indicates 0 degrees despite the actual panel
orientation. The second way to indicate this is in the general features
block, which can just indicate whether 180 degress rotation is used.
The third might be a separate rotation data block, but that is not
at all documented so who knows what it may contain.

Let's try the first two. We first try the DSI specicic VBT
information, and it it doesn't look trustworthy (ie. indicates
0 degrees) we fall back to the 180 degree thing. Just to avoid too
many changes in one go we shall also keep the hardware readout path
for now.

If this works for more than just my VLV FFRD the question becomes
how many of the panel orientation quirks are now redundant?

v2: Move the code into intel_dsi.c (Jani)

Cc: Hans de Goede <[e-mail]>
Reviewed-by: Jani Nikula <[e-mail]>
Signed-off-by: Ville Syrjälä <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Tested-by: Hans de Goede <[e-mail]>

drivers/gpu/drm/i915/i915_drv.h

···
 	unsigned int panel_type:4;
 	int lvds_ssc_freq;
 	unsigned int bios_lvds_val; /* initial [PCH_]LVDS reg val in VBIOS */
+	enum drm_panel_orientation orientation;
 
 	enum drrs_support_type drrs_type;
 
···
 		u8 *data;
 		const u8 *sequence[MIPI_SEQ_MAX];
 		u8 *deassert_seq; /* Used by fixup_mipi_sequences() */
+		enum drm_panel_orientation orientation;
 	} dsi;
 
 	int crt_ddc_pin;

drivers/gpu/drm/i915/intel_bios.c

···
 		intel_bios_ssc_frequency(dev_priv, general->ssc_freq);
 	dev_priv->vbt.display_clock_mode = general->display_clock_mode;
 	dev_priv->vbt.fdi_rx_polarity_inverted = general->fdi_rx_polarity_inverted;
+	if (bdb->version >= 181) {
+		dev_priv->vbt.orientation = general->rotate_180 ?
+			DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP :
+			DRM_MODE_PANEL_ORIENTATION_NORMAL;
+	} else {
+		dev_priv->vbt.orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
+	}
 	DRM_DEBUG_KMS("BDB_GENERAL_FEATURES int_tv_support %d int_crt_support %d lvds_use_ssc %d lvds_ssc_freq %d display_clock_mode %d fdi_rx_polarity_inverted %d\n",
 		      dev_priv->vbt.int_tv_support,
 		      dev_priv->vbt.int_crt_support,
···
 	}
 
 	parse_dsi_backlight_ports(dev_priv, bdb->version, port);
+
+	/* FIXME is the 90 vs. 270 correct? */
+	switch (config->rotation) {
+	case ENABLE_ROTATION_0:
+		/*
+		 * Most (all?) VBTs claim 0 degrees despite having
+		 * an upside down panel, thus we do not trust this.
+		 */
+		dev_priv->vbt.dsi.orientation =
+			DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
+		break;
+	case ENABLE_ROTATION_90:
+		dev_priv->vbt.dsi.orientation =
+			DRM_MODE_PANEL_ORIENTATION_RIGHT_UP;
+		break;
+	case ENABLE_ROTATION_180:
+		dev_priv->vbt.dsi.orientation =
+			DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP;
+		break;
+	case ENABLE_ROTATION_270:
+		dev_priv->vbt.dsi.orientation =
+			DRM_MODE_PANEL_ORIENTATION_LEFT_UP;
+		break;
+	}
 
 	/* We have mandatory mipi config blocks. Initialize as generic panel */
 	dev_priv->vbt.dsi.panel_id = MIPI_DSI_GENERIC_PANEL_ID;

drivers/gpu/drm/i915/intel_dsi.c

···
 
 	return host;
 }
+
+enum drm_panel_orientation
+intel_dsi_get_panel_orientation(struct intel_connector *connector)
+{
+	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
+	enum drm_panel_orientation orientation;
+
+	orientation = dev_priv->vbt.dsi.orientation;
+	if (orientation != DRM_MODE_PANEL_ORIENTATION_UNKNOWN)
+		return orientation;
+
+	orientation = dev_priv->vbt.orientation;
+	if (orientation != DRM_MODE_PANEL_ORIENTATION_UNKNOWN)
+		return orientation;
+
+	return DRM_MODE_PANEL_ORIENTATION_NORMAL;
+}

drivers/gpu/drm/i915/intel_dsi.h

···
 /* intel_dsi.c */
 int intel_dsi_bitrate(const struct intel_dsi *intel_dsi);
 int intel_dsi_tlpx_ns(const struct intel_dsi *intel_dsi);
+enum drm_panel_orientation
+intel_dsi_get_panel_orientation(struct intel_connector *connector);
 
 /* vlv_dsi.c */
 void vlv_dsi_wait_for_fifo_empty(struct intel_dsi *intel_dsi, enum port port);

drivers/gpu/drm/i915/vlv_dsi.c

···
 			return orientation;
 	}
 
-	return DRM_MODE_PANEL_ORIENTATION_NORMAL;
+	return intel_dsi_get_panel_orientation(connector);
 }
 
 static void intel_dsi_add_properties(struct intel_connector *connector)