[Intel-gfx] [RFC PATCH] set DIDL using the ACPI video output device _ADR method return value

[Zhang Rui]

we used to set the DIDL in the output device detected order.
But some BIOSes requires it to be initialized in the ACPI device order.
e.g. the value of the first field in DIDL stands for the first
ACPI video output device in ACPI namespace.

Now we initialize the DIDL using the device id, i.e. _ADR return value,
of each ACPI video device, if it is not 0.
https://bugzilla.kernel.org/show_bug.cgi?id=15054

Signed-off-by: Zhang Rui <rui.zhang at intel.com>
---
 drivers/gpu/drm/i915/i915_opregion.c |   54 ++++++++++++++++++++++++++++++++---
 1 file changed, 50 insertions(+), 4 deletions(-)

Index: linux-2.6/drivers/gpu/drm/i915/i915_opregion.c
===================================================================
--- linux-2.6.orig/drivers/gpu/drm/i915/i915_opregion.c
+++ linux-2.6/drivers/gpu/drm/i915/i915_opregion.c
@@ -382,8 +382,57 @@ static void intel_didl_outputs(struct dr
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_opregion *opregion = &dev_priv->opregion;
 	struct drm_connector *connector;
+	acpi_handle handle;
+	struct acpi_device *acpi_dev, *acpi_cdev, *acpi_video_bus = NULL;
+	unsigned long long device_id;
+	acpi_status status;
 	int i = 0;
 
+	handle = DEVICE_ACPI_HANDLE(&dev->pdev->dev);
+	if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &acpi_dev)))
+		return;
+
+	if (acpi_is_video_device(acpi_dev))
+		acpi_video_bus = acpi_dev;
+	else {
+		list_for_each_entry(acpi_cdev, &acpi_dev->children, node) {
+			if (acpi_is_video_device(acpi_cdev)) {
+				acpi_video_bus = acpi_cdev;
+				break;
+			}
+		}
+	}
+
+	if (!acpi_video_bus) {
+		printk(KERN_WARNING "No ACPI video bus found\n");
+		return;
+	}
+
+	list_for_each_entry(acpi_cdev, &acpi_video_bus->children, node) {
+		if (i >= 8) {
+			dev_printk (KERN_ERR, &dev->pdev->dev,
+				    "More than 8 outputs detected\n");
+			return;
+		}
+		status =
+			acpi_evaluate_integer(acpi_cdev->handle, "_ADR",
+						NULL, &device_id);
+		if (ACPI_SUCCESS(status)) {
+			if (!device_id)
+				goto blind_set;
+			opregion->acpi->didl[i] = (u32)(device_id & 0x0f0f);
+			i++;
+		}
+	}
+
+end:
+	/* If fewer than 8 outputs, the list must be null terminated */
+	if (i < 8)
+		opregion->acpi->didl[i] = 0;
+	return;
+
+blind_set:
+	i = 0;
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
 		int output_type = ACPI_OTHER_OUTPUT;
 		if (i >= 8) {
@@ -416,10 +465,7 @@ static void intel_didl_outputs(struct dr
 		opregion->acpi->didl[i] |= (1<<31) | output_type | i;
 		i++;
 	}
-
-	/* If fewer than 8 outputs, the list must be null terminated */
-	if (i < 8)
-		opregion->acpi->didl[i] = 0;
+	goto end;
 }
 
 int intel_opregion_init(struct drm_device *dev, int resume)