drm/nouveau: less magic DCB 1.5 parsing

This in the very least matches the parsing of all the previously known
entries, and hopefully (at least closer to) correct for any we haven't
seen yet.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_bios.c

@@ -5393,52 +5393,49 @@ static bool
 parse_dcb15_entry(struct drm_device *dev, struct parsed_dcb *dcb,
 		  uint32_t conn, uint32_t conf, struct dcb_entry *entry)
 {
-	if (conn != 0xf0003f00 && conn != 0xf2247f10 && conn != 0xf2204001 &&
-	    conn != 0xf2204301 && conn != 0xf2204311 && conn != 0xf2208001 &&
-	    conn != 0xf2244001 && conn != 0xf2244301 && conn != 0xf2244311 &&
-	    conn != 0xf4204011 && conn != 0xf4208011 && conn != 0xf4248011 &&
-	    conn != 0xf2045ff2 && conn != 0xf2045f14 && conn != 0xf207df14 &&
-	    conn != 0xf2205004 && conn != 0xf2209004) {
-		NV_ERROR(dev, "Unknown DCB 1.5 entry, please report\n");
-
-		/* cause output setting to fail for !TV, so message is seen */
-		if ((conn & 0xf) != 0x1)
-			dcb->entries = 0;
-
-		return false;
-	}
-	/* most of the below is a "best guess" atm */
-	entry->type = conn & 0xf;
-	if (entry->type == 2)
-		/* another way of specifying straps based lvds... */
-		entry->type = OUTPUT_LVDS;
-	if (entry->type == 4) { /* digital */
-		if (conn & 0x10)
+	switch (conn & 0x0000000f) {
+	case 0:
+		entry->type = OUTPUT_ANALOG;
+		break;
+	case 1:
+		entry->type = OUTPUT_TV;
+		break;
+	case 2:
+	case 3:
 		entry->type = OUTPUT_LVDS;
-		else
+		break;
+	case 4:
+		switch ((conn & 0x000000f0) >> 4) {
+		case 0:
 			entry->type = OUTPUT_TMDS;
+			break;
+		case 1:
+			entry->type = OUTPUT_LVDS;
+			break;
+		default:
+			NV_ERROR(dev, "Unknown DCB subtype 4/%d\n",
+				 (conn & 0x000000f0) >> 4);
+			return false;
+		}
+		break;
+	default:
+		NV_ERROR(dev, "Unknown DCB type %d\n", conn & 0x0000000f);
+		return false;
 	}
-	/* what's in bits 5-13? could be some encoder maker thing, in tv case */
-	entry->i2c_index = (conn >> 14) & 0xf;
-	/* raw heads field is in range 0-1, so move to 1-2 */
-	entry->heads = ((conn >> 18) & 0x7) + 1;
-	entry->location = (conn >> 21) & 0xf;
-	/* unused: entry->bus = (conn >> 25) & 0x7; */
-	/* set or to be same as heads -- hopefully safe enough */
-	entry->or = entry->heads;
+
+	entry->i2c_index = (conn & 0x0003c000) >> 14;
+	entry->heads = ((conn & 0x001c0000) >> 18) + 1;
+	entry->or = entry->heads; /* same as heads, hopefully safe enough */
+	entry->location = (conn & 0x01e00000) >> 21;
+	entry->bus = (conn & 0x0e000000) >> 25;
 	entry->duallink_possible = false;
 
 	switch (entry->type) {
 	case OUTPUT_ANALOG:
 		entry->crtconf.maxfreq = (conf & 0xffff) * 10;
 		break;
-	case OUTPUT_LVDS:
-		/*
-		 * This is probably buried in conn's unknown bits.
-		 * This will upset EDID-ful models, if they exist
-		 */
-		entry->lvdsconf.use_straps_for_mode = true;
-		entry->lvdsconf.use_power_scripts = true;
+	case OUTPUT_TV:
+		entry->tvconf.has_component_output = false;
 		break;
 	case OUTPUT_TMDS:
 		/*
@@ -5447,8 +5444,12 @@ parse_dcb15_entry(struct drm_device *dev, struct parsed_dcb *dcb,
 		 */
 		fabricate_vga_output(dcb, entry->i2c_index, entry->heads);
 		break;
-	case OUTPUT_TV:
-		entry->tvconf.has_component_output = false;
+	case OUTPUT_LVDS:
+		if ((conn & 0x00003f00) != 0x10)
+			entry->lvdsconf.use_straps_for_mode = true;
+		entry->lvdsconf.use_power_scripts = true;
+		break;
+	default:
 		break;
 	}