diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml | 18 | ||||
| -rw-r--r-- | Documentation/video4linux/v4l2-controls.txt | 21 |
2 files changed, 13 insertions, 26 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml index 6f1f9a629dc..b17a7aac699 100644 --- a/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml +++ b/Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml @@ -183,7 +183,12 @@ applications must set the array to zero.</entry> <entry>__u32</entry> <entry><structfield>ctrl_class</structfield></entry> <entry>The control class to which all controls belong, see -<xref linkend="ctrl-class" />.</entry> +<xref linkend="ctrl-class" />. Drivers that use a kernel framework for handling +controls will also accept a value of 0 here, meaning that the controls can +belong to any control class. Whether drivers support this can be tested by setting +<structfield>ctrl_class</structfield> to 0 and calling <constant>VIDIOC_TRY_EXT_CTRLS</constant> +with a <structfield>count</structfield> of 0. If that succeeds, then the driver +supports this feature.</entry> </row> <row> <entry>__u32</entry> @@ -194,10 +199,13 @@ also be zero.</entry> <row> <entry>__u32</entry> <entry><structfield>error_idx</structfield></entry> - <entry>Set by the driver in case of an error. It is the -index of the control causing the error or equal to 'count' when the -error is not associated with a particular control. Undefined when the -ioctl returns 0 (success).</entry> + <entry>Set by the driver in case of an error. If it is equal +to <structfield>count</structfield>, then no actual changes were made to +controls. In other words, the error was not associated with setting a particular +control. If it is another value, then only the controls up to <structfield>error_idx-1</structfield> +were modified and control <structfield>error_idx</structfield> is the one that +caused the error. The <structfield>error_idx</structfield> value is undefined +if the ioctl returned 0 (success).</entry> </row> <row> <entry>__u32</entry> diff --git a/Documentation/video4linux/v4l2-controls.txt b/Documentation/video4linux/v4l2-controls.txt index 26aa0573933..e2492a9d102 100644 --- a/Documentation/video4linux/v4l2-controls.txt +++ b/Documentation/video4linux/v4l2-controls.txt @@ -666,27 +666,6 @@ a control of this type whenever the first control belonging to a new control class is added. -Differences from the Spec -========================= - -There are a few places where the framework acts slightly differently from the -V4L2 Specification. Those differences are described in this section. We will -have to see whether we need to adjust the spec or not. - -1) It is no longer required to have all controls contained in a -v4l2_ext_control array be from the same control class. The framework will be -able to handle any type of control in the array. You need to set ctrl_class -to 0 in order to enable this. If ctrl_class is non-zero, then it will still -check that all controls belong to that control class. - -If you set ctrl_class to 0 and count to 0, then it will only return an error -if there are no controls at all. - -2) Clarified the way error_idx works. For get and set it will be equal to -count if nothing was done yet. If it is less than count then only the controls -up to error_idx-1 were successfully applied. - - Proposals for Extensions ======================== |