drm/i915: Move vbt read from firmware to intel_bios.c

VBT read from firmware is currently nested within opregion vbt read.
Extract it and place it together with other vbt read mechanisms and
dis-associate vbt-firmware from opregion structure.

v2: Return NULL in failure cases and use a null check in
    intel_bios_init(Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240228213235.2495611-4-radhakrishna.sripada@intel.com

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

@@ -25,6 +25,8 @@
  *
  */
 
+#include <linux/firmware.h>
+
 #include <drm/display/drm_dp_helper.h>
 #include <drm/display/drm_dsc_helper.h>
 #include <drm/drm_edid.h>
@@ -3000,6 +3002,43 @@ bool intel_bios_is_valid_vbt(struct drm_i915_private *i915,
 	return vbt;
 }
 
+static struct vbt_header *firmware_get_vbt(struct drm_i915_private *i915,
+					   size_t *size)
+{
+	struct vbt_header *vbt = NULL;
+	const struct firmware *fw = NULL;
+	const char *name = i915->display.params.vbt_firmware;
+	int ret;
+
+	if (!name || !*name)
+		return NULL;
+
+	ret = request_firmware(&fw, name, i915->drm.dev);
+	if (ret) {
+		drm_err(&i915->drm,
+			"Requesting VBT firmware \"%s\" failed (%d)\n",
+			name, ret);
+		return NULL;
+	}
+
+	if (intel_bios_is_valid_vbt(i915, fw->data, fw->size)) {
+		vbt = kmemdup(fw->data, fw->size, GFP_KERNEL);
+		if (vbt) {
+			drm_dbg_kms(&i915->drm,
+				    "Found valid VBT firmware \"%s\"\n", name);
+			if (size)
+				*size = fw->size;
+		}
+	} else {
+		drm_dbg_kms(&i915->drm, "Invalid VBT firmware \"%s\"\n",
+			    name);
+	}
+
+	release_firmware(fw);
+
+	return vbt;
+}
+
 static u32 intel_spi_read(struct intel_uncore *uncore, u32 offset)
 {
 	intel_uncore_write(uncore, PRIMARY_SPI_ADDRESS, offset);
@@ -3152,7 +3191,11 @@ void intel_bios_init(struct drm_i915_private *i915)
 
 	init_vbt_defaults(i915);
 
-	vbt = intel_opregion_get_vbt(i915, NULL);
+	oprom_vbt = firmware_get_vbt(i915, NULL);
+	vbt = oprom_vbt;
+
+	if (!vbt)
+		vbt = intel_opregion_get_vbt(i915, NULL);
 
 	/*
 	 * If the OpRegion does not have VBT, look in SPI flash through MMIO or

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

@@ -27,7 +27,6 @@
 
 #include <linux/acpi.h>
 #include <linux/dmi.h>
-#include <linux/firmware.h>
 #include <acpi/video.h>
 
 #include <drm/drm_edid.h>
@@ -263,7 +262,6 @@ struct intel_opregion {
 	struct opregion_asle *asle;
 	struct opregion_asle_ext *asle_ext;
 	void *rvda;
-	void *vbt_firmware;
 	const void *vbt;
 	u32 vbt_size;
 	struct work_struct asle_work;
@@ -869,46 +867,6 @@ static const struct dmi_system_id intel_no_opregion_vbt[] = {
 	{ }
 };
 
-static int intel_load_vbt_firmware(struct drm_i915_private *dev_priv)
-{
-	struct intel_opregion *opregion = dev_priv->display.opregion;
-	const struct firmware *fw = NULL;
-	const char *name = dev_priv->display.params.vbt_firmware;
-	int ret;
-
-	if (!name || !*name)
-		return -ENOENT;
-
-	ret = request_firmware(&fw, name, dev_priv->drm.dev);
-	if (ret) {
-		drm_err(&dev_priv->drm,
-			"Requesting VBT firmware \"%s\" failed (%d)\n",
-			name, ret);
-		return ret;
-	}
-
-	if (intel_bios_is_valid_vbt(dev_priv, fw->data, fw->size)) {
-		opregion->vbt_firmware = kmemdup(fw->data, fw->size, GFP_KERNEL);
-		if (opregion->vbt_firmware) {
-			drm_dbg_kms(&dev_priv->drm,
-				    "Found valid VBT firmware \"%s\"\n", name);
-			opregion->vbt = opregion->vbt_firmware;
-			opregion->vbt_size = fw->size;
-			ret = 0;
-		} else {
-			ret = -ENOMEM;
-		}
-	} else {
-		drm_dbg_kms(&dev_priv->drm, "Invalid VBT firmware \"%s\"\n",
-			    name);
-		ret = -EINVAL;
-	}
-
-	release_firmware(fw);
-
-	return ret;
-}
-
 int intel_opregion_setup(struct drm_i915_private *dev_priv)
 {
 	struct intel_opregion *opregion;
@@ -1006,9 +964,6 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
 		drm_dbg(&dev_priv->drm, "Mailbox #2 for backlight present\n");
 	}
 
-	if (intel_load_vbt_firmware(dev_priv) == 0)
-		goto out;
-
 	if (dmi_check_system(intel_no_opregion_vbt))
 		goto out;
 
@@ -1312,7 +1267,6 @@ void intel_opregion_cleanup(struct drm_i915_private *i915)
 	memunmap(opregion->header);
 	if (opregion->rvda)
 		memunmap(opregion->rvda);
-	kfree(opregion->vbt_firmware);
 	kfree(opregion);
 	i915->display.opregion = NULL;
 }