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[RFCv2,API,28/28] Add vfl_dir field documentation.

Message ID 73a5869ff6f5b11437f0938458e99e0532e70757.1347023744.git.hans.verkuil@cisco.com (mailing list archive)
State New, archived
Headers show

Commit Message

Hans Verkuil Sept. 7, 2012, 1:29 p.m. UTC 
From: Hans Verkuil <hans.verkuil@cisco.com>

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 Documentation/video4linux/v4l2-framework.txt |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
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Patch

diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
index 89318be..20f1c05 100644
--- a/Documentation/video4linux/v4l2-framework.txt
+++ b/Documentation/video4linux/v4l2-framework.txt
@@ -583,11 +583,18 @@  You should also set these fields:
 
 - name: set to something descriptive and unique.
 
+- vfl_dir: set to VFL_DIR_TX for output devices and VFL_DIR_M2M for mem2mem
+  (codec) devices.
+
 - fops: set to the v4l2_file_operations struct.
 
 - 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.
+  future!), then set this to your v4l2_ioctl_ops struct. The vfl_type and
+  vfl_dir fields are used to disable ops that do not match the type/dir
+  combination. E.g. VBI ops are disabled for non-VBI nodes, and output ops
+  are disabled for a capture device. This makes it possible to provide
+  just one v4l2_ioctl_ops struct for both vbi and video nodes.
 
 - lock: leave to NULL if you want to do all the locking in the driver.
   Otherwise you give it a pointer to a struct mutex_lock and before the