merge: http://linuxtv.org/hg/~awalls/v4l-dvb

From: Mauro Carvalho Chehab <mchehab@redhat.com>

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 31 insertions, 3 deletions

diff --git a/linux/Documentation/video4linux/v4l2-framework.txt b/linux/Documentation/video4linux/v4l2-framework.txt
index accc376e9..4207590b2 100644
--- a/linux/Documentation/video4linux/v4l2-framework.txt
+++ b/linux/Documentation/video4linux/v4l2-framework.txt
@@ -91,7 +91,13 @@ NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register.
 
 The first 'dev' argument is normally the struct device pointer of a pci_dev,
 usb_device or platform_device. It is rare for dev to be NULL, but it happens
-with ISA devices, for example.
+with ISA devices or when one device creates multiple PCI devices, thus making
+it impossible to associate v4l2_dev with a particular parent.
+
+You can also supply a notify() callback that can be called by sub-devices to
+notify you of events. Whether you need to set this depends on the sub-device.
+Any notifications a sub-device supports must be defined in a header in
+include/media/<subdevice>.h.
 
 You unregister with:
 
@@ -280,6 +286,11 @@ e.g. AUDIO_CONTROLLER and specify that as the group ID value when calling
 v4l2_device_call_all(). That ensures that it will only go to the subdev
 that needs it.
 
+If the sub-device needs to notify its v4l2_device parent of an event, then
+it can call v4l2_subdev_notify(sd, notification, arg). This macro checks
+whether there is a notify() callback defined and returns -ENODEV if not.
+Otherwise the result of the notify() call is returned.
+
 The advantage of using v4l2_subdev is that it is a generic struct and does
 not contain any knowledge about the underlying hardware. So a driver might
 contain several subdevs that use an I2C bus, but also a subdev that is
@@ -359,8 +370,8 @@ This loads the given module (can be NULL if no module needs to be loaded) and
 calls i2c_new_device() with the given i2c_adapter and chip/address arguments.
 If all goes well, then it registers the subdev with the v4l2_device. It gets
 the v4l2_device by calling i2c_get_adapdata(adapter), so you should make sure
-that adapdata is set to v4l2_device when you setup the i2c_adapter in your
-driver.
+to call i2c_set_adapdata(adapter, v4l2_device) when you setup the i2c_adapter
+in your driver.
 
 You can also use v4l2_i2c_new_probed_subdev() which is very similar to
 v4l2_i2c_new_subdev(), except that it has an array of possible I2C addresses
@@ -368,6 +379,14 @@ that it should probe. Internally it calls i2c_new_probed_device().
 
 Both functions return NULL if something went wrong.
 
+Note that the chipid you pass to v4l2_i2c_new_(probed_)subdev() is usually
+the same as the module name. It allows you to specify a chip variant, e.g.
+"saa7114" or "saa7115". In general though the i2c driver autodetects this.
+The use of chipid is something that needs to be looked at more closely at a
+later date. It differs between i2c drivers and as such can be confusing.
+To see which chip variants are supported you can look in the i2c driver code
+for the i2c_device_id table. This lists all the possibilities.
+
 
 struct video_device
 -------------------
@@ -406,6 +425,15 @@ You should also set these fields:
 - ioctl_ops: if you use the v4l2_ioctl_ops to simplify ioctl maintenance
   (highly recommended to use this and it might become compulsory in the
   future!), then set this to your v4l2_ioctl_ops struct.
+- parent: you only set this if v4l2_device was registered with NULL as
+  the parent device struct. This only happens in cases where one hardware
+  device has multiple PCI devices that all share the same v4l2_device core.
+
+  The cx88 driver is an example of this: one core v4l2_device struct, but
+  it is used by both an raw video PCI device (cx8800) and a MPEG PCI device
+  (cx8802). Since the v4l2_device cannot be associated with a particular
+  PCI device it is setup without a parent device. But when the struct
+  video_device is setup you do know which parent PCI device to use.
 
 If you use v4l2_ioctl_ops, then you should set either .unlocked_ioctl or
 .ioctl to video_ioctl2 in your v4l2_file_operations struct.