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V4L/DVB (10980): doc: improve the v4l2-framework documentation.

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Emphasize the need to call i2c_set_adapdata and clarify the use of the
chipid in v4l2_i2c_new_(probed_)device().

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2009-03-12 18:34:19 -03:00 committed by Mauro Carvalho Chehab
parent 5e585ef15b
commit 2c79252326
1 changed files with 10 additions and 2 deletions
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12
Documentation/video4linux/v4l2-framework.txt
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@ -359,8 +359,8 @@ 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 +368,14 @@ 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
-------------------