linux-kernel - [PATCH 2/2] media: uvcvideo: UVC minimum relative pan/tilt/zoom speed fix

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Message-Id: <20240328-uvc-fix-relative-ptz-speed-v1-2-17373eb8b2be@securitylive.com>
Date: Thu, 28 Mar 2024 18:18:07 -0500
From: John Bauer via B4 Relay <devnull+johnebgood.securitylive.com@...nel.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linh.tp.vu@...il.com, ribalda@...omium.org, soyer@....hu, 
 John Bauer <johnebgood@...uritylive.com>
Subject: [PATCH 2/2] media: uvcvideo: UVC minimum relative pan/tilt/zoom
 speed fix

From: John Bauer <johnebgood@...uritylive.com>

Made recommended changes from Ricardo. I explored the case where
the minimum could be > 0 but less than the maximum. If this were
to occur the range of -maximum to maximum would still apply correctly
however there would be a range from -min to min that would possibly
not apply. It would be possible to capture the probed minimum and
check against that when setting the controls.

Signed-off-by: John Bauer <johnebgood@...uritylive.com>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index b389ab3ee05d..04300a782c81 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1322,6 +1322,10 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 		break;
 	}
 
+	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)
+		v4l2_ctrl->maximum = mapping->get(mapping, UVC_GET_MAX,
+				     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
+
 	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN) {
 		switch (v4l2_ctrl->id) {
 		case V4L2_CID_ZOOM_CONTINUOUS:
@@ -1332,8 +1336,7 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 			 * value cannot be probed so it becomes the additive
 			 * inverse of maximum.
 			 */
-			v4l2_ctrl->minimum = -1 * mapping->get(mapping, UVC_GET_MAX,
-						uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
+			v4l2_ctrl->minimum = -v4l2_ctrl->maximum;
 			break;
 		default:
 			v4l2_ctrl->minimum = mapping->get(mapping, UVC_GET_MIN,
@@ -1342,10 +1345,6 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 		}
 	}
 
-	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)
-		v4l2_ctrl->maximum = mapping->get(mapping, UVC_GET_MAX,
-				     uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
-
 	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES)
 		v4l2_ctrl->step = mapping->get(mapping, UVC_GET_RES,
 				  uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
@@ -1940,7 +1939,7 @@ int uvc_ctrl_set(struct uvc_fh *handle,
 		case V4L2_CID_ZOOM_CONTINUOUS:
 		case V4L2_CID_PAN_SPEED:
 		case V4L2_CID_TILT_SPEED:
-			min = max * -1;
+			min = -max;
 		default:
 			break;
 		}

-- 
2.34.1