From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E36CC432C2 for ; Wed, 25 Sep 2019 15:17:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6BDE62054F for ; Wed, 25 Sep 2019 15:17:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439184AbfIYPR0 (ORCPT ); Wed, 25 Sep 2019 11:17:26 -0400 Received: from lb2-smtp-cloud9.xs4all.net ([194.109.24.26]:39071 "EHLO lb2-smtp-cloud9.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726496AbfIYPR0 (ORCPT ); Wed, 25 Sep 2019 11:17:26 -0400 Received: from [192.168.2.10] ([46.9.232.237]) by smtp-cloud9.xs4all.net with ESMTPA id D92eiLFFSz6EAD92hiBWC5; Wed, 25 Sep 2019 17:17:24 +0200 Subject: Re: [PATCH] media: vidioc-queryctrl.rst: clarify combining READ_ONLY with WRITE_ONLY To: Helen Koike , mchehab@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@collabora.com References: <20190925150945.27706-1-helen.koike@collabora.com> From: Hans Verkuil Message-ID: <211b3d26-ffbc-3245-6613-7fd42c65cc80@xs4all.nl> Date: Wed, 25 Sep 2019 17:17:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190925150945.27706-1-helen.koike@collabora.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfO+ibsMf9ShsmwQnFbBeOlb0AhnOcX4lBpawYBQHV+RFyXgynEUjzDZ67k5FScg4zIKunKlSsjGNaRBoJmxicNR7W3WiznZZpvE2fjPUBitpvlneleGK YVKz4zxeOHOzWpbHkeEl37M41gSsqbg08wvhvSghwM4bXONmAUkIlk0IZ0GT8nd7H/ylhDWvJUfEmahCW59UPUZitKR/TftOViXyLhGlZGT7Kr0t8NW/x57n Wnxtn9Z+nkyMyHbnkJTYNb+1I57CFqayEghVK2pncaruN0FzpHfkLS07jFG2HPz7pmQ3JOjCrcLhIRexw0aULqcXpvKTWAfgmLuxww+Y3PE= Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 9/25/19 5:09 PM, Helen Koike wrote: > Make it clear in the documentation that V4L2_CTRL_FLAG_READ_ONLY doesn't > conflict with V4L2_CTRL_FLAG_WRITE_ONLY. Also make it clear that > if both are combined then the control has read and write permissions. That doesn't look right. This is the test in v4l2-compliance: __u32 rw_mask = V4L2_CTRL_FLAG_READ_ONLY | V4L2_CTRL_FLAG_WRITE_ONLY; if ((fl & rw_mask) == rw_mask) return fail("can't read nor write this control\n"); If both flags are set, then a fail is reported. Did you mis-read? Setting both flags makes no sense. Regards, Hans > > Signed-off-by: Helen Koike > > --- > Hi, > > v4l2-compliance expects both flags for read and write permissions, so I > would like to make it clear in the docs. > Please let me know if this is not the case. > > Thanks > Helen > --- > Documentation/media/uapi/v4l/vidioc-queryctrl.rst | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst b/Documentation/media/uapi/v4l/vidioc-queryctrl.rst > index a3d56ffbf4cc..1d3aecdf679f 100644 > --- a/Documentation/media/uapi/v4l/vidioc-queryctrl.rst > +++ b/Documentation/media/uapi/v4l/vidioc-queryctrl.rst > @@ -500,6 +500,11 @@ See also the examples in :ref:`control`. > - 0x0004 > - This control is permanently readable only. Any attempt to change > the control will result in an ``EINVAL`` error code. > + > + .. note:: > + > + If combined with ``V4L2_CTRL_FLAG_WRITE_ONLY``, then both, read > + and write are allowed. > * - ``V4L2_CTRL_FLAG_UPDATE`` > - 0x0008 > - A hint that changing this control may affect the value of other > @@ -523,6 +528,11 @@ See also the examples in :ref:`control`. > where writing a value will cause the device to carry out a given > action (e. g. motor control) but no meaningful value can be > returned. > + > + .. note:: > + > + If combined with ``V4L2_CTRL_FLAG_READ_ONLY``, then both, read > + and write are allowed. > * - ``V4L2_CTRL_FLAG_VOLATILE`` > - 0x0080 > - This control is volatile, which means that the value of the >