drm/i915: Check LSPCON vendor OUI

Intel LSPCON chip is provided by 2 vendors:
- Megachips America (MCA)
- Parade technologies (Parade tech)

Its important to know the vendor of this chip, as the address to
write AVI infoframes is different for those two.

This patch reads the vendor OUI signature, and marks into LSPCON
encoder structure for future usages.

This patch also does a small re-arrangement of the code, by moving
lspcon mode change into probe function.

V2: Use dp->desc for OUI detection, dont add a helper for this
    (Ville)
V3: Rebase, Added r-b from Maarten
V4: Rebase
V5: Rebase
V6: Rebase
V7: Rebase
V8: Rebase
V9: Rebase
V10: Rebase

Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1539325394-20788-4-git-send-email-shashank.sharma@intel.com

drivers/gpu/drm/i915/intel_drv.h

@@ -1162,9 +1162,15 @@ struct intel_dp {
 	struct intel_dp_compliance compliance;
 };
 
+enum lspcon_vendor {
+	LSPCON_VENDOR_MCA,
+	LSPCON_VENDOR_PARADE
+};
+
 struct intel_lspcon {
 	bool active;
 	enum drm_lspcon_mode mode;
+	enum lspcon_vendor vendor;
 };
 
 struct intel_digital_port {

drivers/gpu/drm/i915/intel_lspcon.c

@@ -27,6 +27,10 @@
 #include <drm/drm_dp_dual_mode_helper.h>
 #include "intel_drv.h"
 
+/* LSPCON OUI Vendor ID(signatures) */
+#define LSPCON_VENDOR_PARADE_OUI 0x001CF8
+#define LSPCON_VENDOR_MCA_OUI 0x0060AD
+
 static struct intel_dp *lspcon_to_intel_dp(struct intel_lspcon *lspcon)
 {
 	struct intel_digital_port *dig_port =
@@ -50,6 +54,40 @@ static const char *lspcon_mode_name(enum drm_lspcon_mode mode)
 	}
 }
 
+static bool lspcon_detect_vendor(struct intel_lspcon *lspcon)
+{
+	struct intel_dp *dp = lspcon_to_intel_dp(lspcon);
+	struct drm_dp_dpcd_ident *ident;
+	u32 vendor_oui;
+
+	if (drm_dp_read_desc(&dp->aux, &dp->desc, drm_dp_is_branch(dp->dpcd))) {
+		DRM_ERROR("Can't read description\n");
+		return false;
+	}
+
+	ident = &dp->desc.ident;
+	vendor_oui = (ident->oui[0] << 16) | (ident->oui[1] << 8) |
+		      ident->oui[2];
+
+	switch (vendor_oui) {
+	case LSPCON_VENDOR_MCA_OUI:
+		lspcon->vendor = LSPCON_VENDOR_MCA;
+		DRM_DEBUG_KMS("Vendor: Mega Chips\n");
+		break;
+
+	case LSPCON_VENDOR_PARADE_OUI:
+		lspcon->vendor = LSPCON_VENDOR_PARADE;
+		DRM_DEBUG_KMS("Vendor: Parade Tech\n");
+		break;
+
+	default:
+		DRM_ERROR("Invalid/Unknown vendor OUI\n");
+		return false;
+	}
+
+	return true;
+}
+
 static enum drm_lspcon_mode lspcon_get_current_mode(struct intel_lspcon *lspcon)
 {
 	enum drm_lspcon_mode current_mode;
@@ -159,7 +197,18 @@ static bool lspcon_probe(struct intel_lspcon *lspcon)
 	/* Yay ... got a LSPCON device */
 	DRM_DEBUG_KMS("LSPCON detected\n");
 	lspcon->mode = lspcon_wait_mode(lspcon, expected_mode);
-	lspcon->active = true;
+
+	/*
+	 * In the SW state machine, lets Put LSPCON in PCON mode only.
+	 * In this way, it will work with both HDMI 1.4 sinks as well as HDMI
+	 * 2.0 sinks.
+	 */
+	if (lspcon->active && lspcon->mode != DRM_LSPCON_MODE_PCON) {
+		if (lspcon_change_mode(lspcon, DRM_LSPCON_MODE_PCON) < 0) {
+			DRM_ERROR("LSPCON mode change to PCON failed\n");
+			return false;
+		}
+	}
 	return true;
 }
 
@@ -230,25 +279,17 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port)
 		return false;
 	}
 
-	/*
-	* In the SW state machine, lets Put LSPCON in PCON mode only.
-	* In this way, it will work with both HDMI 1.4 sinks as well as HDMI
-	* 2.0 sinks.
-	*/
-	if (lspcon->active && lspcon->mode != DRM_LSPCON_MODE_PCON) {
-		if (lspcon_change_mode(lspcon, DRM_LSPCON_MODE_PCON) < 0) {
-			DRM_ERROR("LSPCON mode change to PCON failed\n");
-			return false;
-		}
-	}
-
 	if (!intel_dp_read_dpcd(dp)) {
 		DRM_ERROR("LSPCON DPCD read failed\n");
 		return false;
 	}
 
-	drm_dp_read_desc(&dp->aux, &dp->desc, drm_dp_is_branch(dp->dpcd));
+	if (!lspcon_detect_vendor(lspcon)) {
+		DRM_ERROR("LSPCON vendor detection failed\n");
+		return false;
+	}
 
+	lspcon->active = true;
 	DRM_DEBUG_KMS("Success: LSPCON init\n");
 	return true;
 }