From 8c42694150c27ea68a8d46996d943918c769d1d0 Mon Sep 17 00:00:00 2001
From: Ricardo Ribalda <ribalda@chromium.org>
Date: Fri, 18 Jun 2021 14:29:18 +0200
Subject: media: docs: Document the behaviour of uvcvideo driver

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 -EACCES in those cases.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst      | 3 +++
 Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst | 3 +++
 2 files changed, 6 insertions(+)

(limited to 'Documentation/userspace-api')

diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst b/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst
index 80e8c63d530f..fd09677f64f8 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-g-ctrl.rst
@@ -95,3 +95,6 @@ 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 caching the new value until the control is active again.
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 2d6bc8d94380..fdde0ae6d521 100644
--- a/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
+++ b/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst
@@ -470,3 +470,6 @@ 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 caching the new value until the control is active again.
-- 
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