1 files changed, 31 insertions, 15 deletions

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index e144f033f4b5..639d45c1dd2e 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -1341,6 +1341,7 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
 	return;
 }
 
+/* Common defaults which may be overridden by VBT. */
 static void
 init_vbt_defaults(struct drm_i915_private *dev_priv)
 {
@@ -1377,6 +1378,18 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
 			&dev_priv->vbt.ddi_port_info[port];
 
 		info->hdmi_level_shift = HDMI_LEVEL_SHIFT_UNKNOWN;
+	}
+}
+
+/* Defaults to initialize only if there is no VBT. */
+static void
+init_vbt_missing_defaults(struct drm_i915_private *dev_priv)
+{
+	enum port port;
+
+	for (port = PORT_A; port < I915_MAX_PORTS; port++) {
+		struct ddi_vbt_port_info *info =
+			&dev_priv->vbt.ddi_port_info[port];
 
 		info->supports_dvi = (port != PORT_A && port != PORT_E);
 		info->supports_hdmi = info->supports_dvi;
@@ -1462,36 +1475,35 @@ static const struct vbt_header *find_vbt(void __iomem *bios, size_t size)
  * intel_bios_init - find VBT and initialize settings from the BIOS
  * @dev_priv: i915 device instance
  *
- * Loads the Video BIOS and checks that the VBT exists.  Sets scratch registers
- * to appropriate values.
- *
- * Returns 0 on success, nonzero on failure.
+ * Parse and initialize settings from the Video BIOS Tables (VBT). If the VBT
+ * was not found in ACPI OpRegion, try to find it in PCI ROM first. Also
+ * initialize some defaults if the VBT is not present at all.
  */
-int
-intel_bios_init(struct drm_i915_private *dev_priv)
+void intel_bios_init(struct drm_i915_private *dev_priv)
 {
 	struct pci_dev *pdev = dev_priv->drm.pdev;
 	const struct vbt_header *vbt = dev_priv->opregion.vbt;
 	const struct bdb_header *bdb;
 	u8 __iomem *bios = NULL;
 
-	if (HAS_PCH_NOP(dev_priv))
-		return -ENODEV;
+	if (HAS_PCH_NOP(dev_priv)) {
+		DRM_DEBUG_KMS("Skipping VBT init due to disabled display.\n");
+		return;
+	}
 
 	init_vbt_defaults(dev_priv);
 
+	/* If the OpRegion does not have VBT, look in PCI ROM. */
 	if (!vbt) {
 		size_t size;
 
 		bios = pci_map_rom(pdev, &size);
 		if (!bios)
-			return -1;
+			goto out;
 
 		vbt = find_vbt(bios, size);
-		if (!vbt) {
-			pci_unmap_rom(pdev, bios);
-			return -1;
-		}
+		if (!vbt)
+			goto out;
 
 		DRM_DEBUG_KMS("Found valid VBT in PCI ROM\n");
 	}
@@ -1516,10 +1528,14 @@ intel_bios_init(struct drm_i915_private *dev_priv)
 	parse_mipi_sequence(dev_priv, bdb);
 	parse_ddi_ports(dev_priv, bdb);
 
+out:
+	if (!vbt) {
+		DRM_INFO("Failed to find VBIOS tables (VBT)\n");
+		init_vbt_missing_defaults(dev_priv);
+	}
+
 	if (bios)
 		pci_unmap_rom(pdev, bios);
-
-	return 0;
 }
 
 /**