Subject: [PATCH] [acpi video] Add probing capabilities to video device driver

- Add video_dev_test() that checks for _ADR function, which is
  the only known way of determining whether or not a particular
  ACPI object is a video device (and that it is under a video bus
  device).
- Add video_probe() that calls video_dev_test(), and checks that
  the parent device is bound to the "video_bus" driver.

Signed-off-by: Patrick Mochel <mochel@linux.intel.com>

---

 drivers/acpi/drivers/video/dev-device.c |   30 ++++++++++++++++++++++++++++++
 drivers/acpi/drivers/video/dev-driver.c |   22 +++++++++++++++++++++-
 drivers/acpi/drivers/video/video.h      |    3 +++
 3 files changed, 54 insertions(+), 1 deletions(-)

applies-to: 96aaadec677cf56ebd1a9e9a6035648f76d2ec13
3a513703d7c0ca3a4c83a9a9161a445d9c80a9d7
diff --git a/drivers/acpi/drivers/video/dev-device.c b/drivers/acpi/drivers/video/dev-device.c
index de96792..5907c16 100644
--- a/drivers/acpi/drivers/video/dev-device.c
+++ b/drivers/acpi/drivers/video/dev-device.c
@@ -12,3 +12,33 @@
 
 #include <acpi/device.h>
 #include "video.h"
+
+
+static int get_int(struct acpi_dev * ad, char * method, unsigned long * val)
+{
+	acpi_status status;
+
+	status = acpi_evaluate_integer(ad->acpi_device->handle, method,
+				       NULL, val);
+	return ACPI_SUCCESS(status) ? 0 : -ENODEV;
+}
+
+
+/**
+ *	video_dev_test - Determine whether this is a video device
+ *	@ad:	The ACPI device that we're testing
+ *
+ *	Check if this is a video device as best as we can, which 
+ *	solely involves checking for the existence of the _ADR
+ *	method.
+ *
+ *	Returns %0/%1 depending on whether we think it's a video
+ *	device or not.
+ */
+
+int video_dev_test(struct acpi_dev * ad)
+{
+	unsigned long device_id;
+
+	return get_int(ad, "_ADR", &device_id) == 0 ? 1 : 0;
+}
diff --git a/drivers/acpi/drivers/video/dev-driver.c b/drivers/acpi/drivers/video/dev-driver.c
index 750220c..584dfbb 100644
--- a/drivers/acpi/drivers/video/dev-driver.c
+++ b/drivers/acpi/drivers/video/dev-driver.c
@@ -14,6 +14,27 @@
 #include <acpi/driver.h>
 #include "video.h"
 
+static int video_probe(struct acpi_dev * ad)
+{
+	/*
+	 * Unfortunately, video devices do not have any unique 
+	 * distinguishing feature (like a HID). 
+	 * So, we do two things to determine whether or not this
+	 * is a video device.
+	 * - Verify that the parent to this device is bound to the
+	 *   "video_bus" driver.
+	 * - Make sure that the device has an _ADR method.
+	 */
+	if (ad->dev.parent && ad->dev.parent->driver) {
+		if (!strcmp(ad->dev.parent->driver->name, "video_bus"))
+			goto CheckAdr;
+		return 0;
+	}
+
+ CheckAdr:
+	return video_dev_test(ad);
+}
+
 static int video_add(struct acpi_dev * ad)
 {
 	struct acpi_video_dev * vd;
@@ -40,7 +61,6 @@ static int video_remove(struct acpi_dev 
 	return 0;
 }
 
-acpi_no_probe(video);
 acpi_no_start(video);
 acpi_no_stop(video);
 acpi_no_shutdown(video);
diff --git a/drivers/acpi/drivers/video/video.h b/drivers/acpi/drivers/video/video.h
index bf6a593..1c3c061 100644
--- a/drivers/acpi/drivers/video/video.h
+++ b/drivers/acpi/drivers/video/video.h
@@ -29,6 +29,9 @@ struct acpi_video_dev {
 	struct acpi_dev		* v_ad;
 };
 
+extern int video_dev_test(struct acpi_dev * ad);
+
+
 struct acpi_video_enum {
 	union {
 		struct {
---
0.99.9.GIT