drm/i915/display: Add HDR Capability detection for LSPCON

LSPCON firmware exposes HDR capability through LPCON_CAPABILITIES
DPCD register. LSPCON implementations capable of supporting
HDR set HDR_CAPABILITY bit in LSPCON_CAPABILITIES to 1. This patch
reads the same, detects the HDR capability and adds this to
intel_lspcon struct.

v2: Addressed Jani Nikula's review comment and fixed the HDR
    capability detection logic

v3: Deferred HDR detection from lspcon_init (Ville)

v4: Addressed Ville's minor review comments, added his RB.
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201130204738.2443-2-uma.shankar@intel.com

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1452,6 +1452,7 @@ enum lspcon_vendor {
 
 struct intel_lspcon {
 	bool active;
+	bool hdr_supported;
 	enum drm_lspcon_mode mode;
 	enum lspcon_vendor vendor;
 };

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

@@ -35,6 +35,8 @@
 #define LSPCON_VENDOR_PARADE_OUI 0x001CF8
 #define LSPCON_VENDOR_MCA_OUI 0x0060AD
 
+#define DPCD_MCA_LSPCON_HDR_STATUS	0x70003
+
 /* AUX addresses to write MCA AVI IF */
 #define LSPCON_MCA_AVI_IF_WRITE_OFFSET 0x5C0
 #define LSPCON_MCA_AVI_IF_CTRL 0x5DF
@@ -104,6 +106,31 @@ static bool lspcon_detect_vendor(struct intel_lspcon *lspcon)
 	return true;
 }
 
+void lspcon_detect_hdr_capability(struct intel_lspcon *lspcon)
+{
+	struct intel_digital_port *dig_port =
+		container_of(lspcon, struct intel_digital_port, lspcon);
+	struct drm_device *dev = dig_port->base.base.dev;
+	struct intel_dp *dp = lspcon_to_intel_dp(lspcon);
+	u8 hdr_caps;
+	int ret;
+
+	/* Enable HDR for MCA based LSPCON devices */
+	if (lspcon->vendor == LSPCON_VENDOR_MCA)
+		ret = drm_dp_dpcd_read(&dp->aux, DPCD_MCA_LSPCON_HDR_STATUS,
+				       &hdr_caps, 1);
+	else
+		return;
+
+	if (ret < 0) {
+		drm_dbg_kms(dev, "HDR capability detection failed\n");
+		lspcon->hdr_supported = false;
+	} else if (hdr_caps & 0x1) {
+		drm_dbg_kms(dev, "LSPCON capable of HDR\n");
+		lspcon->hdr_supported = true;
+	}
+}
+
 static enum drm_lspcon_mode lspcon_get_current_mode(struct intel_lspcon *lspcon)
 {
 	enum drm_lspcon_mode current_mode;

drivers/gpu/drm/i915/display/intel_lspcon.h

@@ -15,6 +15,7 @@ struct intel_digital_port;
 struct intel_encoder;
 struct intel_lspcon;
 
+void lspcon_detect_hdr_capability(struct intel_lspcon *lspcon);
 void lspcon_resume(struct intel_digital_port *dig_port);
 void lspcon_wait_pcon_mode(struct intel_lspcon *lspcon);
 void lspcon_write_infoframe(struct intel_encoder *encoder,