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([38.81.85.65]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8a860f882ddsm45777777b3.21.2026.09.28.08.24.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 08:24:18 -0700 (PDT) From: Michael Jordan To: Laurent Pinchart , Hans de Goede , Ricardo Ribalda Cc: Mauro Carvalho Chehab , Hans Verkuil , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Michael Jordan , Hans de Goede Subject: [PATCH v3 1/4] media: uvcvideo: report AUTO_UPDATE controls as volatile Date: Mon, 28 Sep 2026 11:24:13 -0400 Message-ID: <20260928152416.766957-2-jordan.mymail@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260928152416.766957-1-jordan.mymail@gmail.com> References: <20260928152416.766957-1-jordan.mymail@gmail.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit uvcvideo re-reads controls flagged UVC_CTRL_FLAG_AUTO_UPDATE from the device instead of trusting its cache, as the device may change their value on its own. That is what V4L2_CTRL_FLAG_VOLATILE describes, but the driver does not report it to userspace. Report V4L2_CTRL_FLAG_VOLATILE for AUTO_UPDATE controls. Writes to a volatile control are ignored unless V4L2_CTRL_FLAG_EXECUTE_ON_WRITE is also set, and uvcvideo sends every write to the device, so also report EXECUTE_ON_WRITE when the control is writable. Suggested-by: Ricardo Ribalda Reviewed-by: Ricardo Ribalda Reviewed-by: Hans de Goede Assisted-by: Claude:claude-fable-5 Signed-off-by: Michael Jordan --- drivers/media/usb/uvc/uvc_ctrl.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index 3ca108b83f1d..aceb263103e9 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -1840,6 +1840,17 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain, if ((ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX) && (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN)) v4l2_ctrl->flags |= V4L2_CTRL_FLAG_HAS_WHICH_MIN_MAX; + if (ctrl->info.flags & UVC_CTRL_FLAG_AUTO_UPDATE) { + v4l2_ctrl->flags |= V4L2_CTRL_FLAG_VOLATILE; + /* + * Writes to a volatile control are documented to be ignored + * unless EXECUTE_ON_WRITE is also reported. The driver sends + * every write of a writable control to the device, so report + * the flag accordingly. + */ + if (ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR) + v4l2_ctrl->flags |= V4L2_CTRL_FLAG_EXECUTE_ON_WRITE; + } if (mapping->master_id) __uvc_find_control(ctrl->entity, mapping->master_id, -- 2.43.0