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Subject[PATCH v7 14/17] media: docs: Document the behaviour of uvcdriver
Date
The uvc driver relies on the camera firmware to keep the control states
and therefore is not capable of changing an inactive control.

Allow returning -EACESS in those cases.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst | 5 +++++
Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst | 5 +++++
2 files changed, 10 insertions(+)

diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst b/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst
index 4f1bed53fad5..8c0a203385c2 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst
@@ -95,3 +95,8 @@ EBUSY

EACCES
Attempt to set a read-only control or to get a write-only control.
+
+ Or if there is an attempt to set an inactive control and the driver is
+ not capable of keeping the new value until the control is active again.
+ This is the case for drivers that do not use the standard control
+ framework and rely purely on the hardware to keep the controls' state.
diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst b/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
index b9c62affbb5a..bb7de7a25241 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
@@ -438,3 +438,8 @@ EACCES

Or the ``which`` field was set to ``V4L2_CTRL_WHICH_REQUEST_VAL`` but the
device does not support requests.
+
+ Or if there is an attempt to set an inactive control and the driver is
+ not capable of keeping the new value until the control is active again.
+ This is the case for drivers that do not use the standard control
+ framework and rely purely on the hardware to keep the controls' state.
--
2.31.0.rc2.261.g7f71774620-goog
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