linux-kernel - [PATCH v3 11/12] media: uvcvideo: Use current

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Message-Id: <20250926-uvc-orientation-v3-11-6dc2fa5b4220@chromium.org>
Date: Fri, 26 Sep 2025 13:11:35 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Hans de Goede <hansg@...nel.org>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
 Robert Moore <robert.moore@...el.com>, Hans Verkuil <hverkuil@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-usb@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-gpio@...r.kernel.org, linux-acpi@...r.kernel.org, 
 acpica-devel@...ts.linux.dev, Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH v3 11/12] media: uvcvideo: Use current_value for read-only
 controls

For read-only controls that do not support GET_MIN, GET_DEF, GET_MAX or
GET_RES use the current value of the control or a constant number if the
current value is not available.

Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 76 +++++++++++++++++++++++++++++-----------
 1 file changed, 56 insertions(+), 20 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 017165a5c94459f1befd4c08f85a2017c58d61e6..e99fdf4bafbea662556798fe345a48b9ffd8467b 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1548,6 +1548,50 @@ static u32 uvc_get_ctrl_bitmap(struct uvc_control *ctrl,
 	return ~0;
 }
 
+static s64 uvc_queryctrl_single_boundary(struct uvc_video_chain *chain,
+					 struct uvc_control *ctrl,
+					 struct uvc_control_mapping *mapping,
+					 u8 op)
+{
+	static const u32 query_types[][3] = {
+		{UVC_CTRL_FLAG_GET_DEF, UVC_GET_DEF, UVC_CTRL_DATA_DEF},
+		{UVC_CTRL_FLAG_GET_MIN, UVC_GET_MIN, UVC_CTRL_DATA_MIN},
+		{UVC_CTRL_FLAG_GET_MAX, UVC_GET_MAX, UVC_CTRL_DATA_MAX},
+		{UVC_CTRL_FLAG_GET_RES, UVC_GET_RES, UVC_CTRL_DATA_RES},
+	};
+	int idx = -1;
+
+	for (unsigned int i = 0; i < ARRAY_SIZE(query_types); i++) {
+		if (op == query_types[i][1]) {
+			idx = i;
+			break;
+		}
+	}
+	if (WARN_ON(idx == -1))
+		return 0;
+
+	if (ctrl->info.flags & query_types[idx][0]) {
+		return uvc_mapping_get_s32(mapping, query_types[idx][1],
+					   uvc_ctrl_data(ctrl,
+							 query_types[idx][2]));
+	}
+
+	/* Use 1 as the default step value.  */
+	if (op == UVC_GET_RES)
+		return 1;
+
+	/* Read-only controls can use GET_CUR as min, max and def. */
+	if (!(ctrl->info.flags & UVC_CTRL_FLAG_SET_CUR) &&
+	    (ctrl->info.flags & UVC_CTRL_FLAG_GET_CUR) &&
+	    __uvc_ctrl_load_cur(chain, ctrl) == 0) {
+		return uvc_mapping_get_s32(mapping, UVC_GET_CUR,
+				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_CURRENT));
+	}
+
+	/* Otherwise, use 0 as last resource. */
+	return 0;
+}
+
 /*
  * Maximum retry count to avoid spurious errors with controls. Increasing this
  * value does no seem to produce better results in the tested hardware.
@@ -1573,11 +1617,9 @@ static int __uvc_queryctrl_boundaries(struct uvc_video_chain *chain,
 			return ret;
 	}
 
-	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_DEF)
-		v4l2_ctrl->default_value = uvc_mapping_get_s32(mapping,
-				UVC_GET_DEF, uvc_ctrl_data(ctrl, UVC_CTRL_DATA_DEF));
-	else
-		v4l2_ctrl->default_value = 0;
+	v4l2_ctrl->default_value =
+		uvc_queryctrl_single_boundary(chain, ctrl, mapping,
+					      UVC_GET_DEF);
 
 	switch (mapping->v4l2_type) {
 	case V4L2_CTRL_TYPE_MENU:
@@ -1608,23 +1650,17 @@ static int __uvc_queryctrl_boundaries(struct uvc_video_chain *chain,
 		break;
 	}
 
-	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MIN)
-		v4l2_ctrl->minimum = uvc_mapping_get_s32(mapping, UVC_GET_MIN,
-				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MIN));
-	else
-		v4l2_ctrl->minimum = 0;
+	v4l2_ctrl->minimum =
+		uvc_queryctrl_single_boundary(chain, ctrl, mapping,
+					      UVC_GET_MIN);
 
-	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_MAX)
-		v4l2_ctrl->maximum = uvc_mapping_get_s32(mapping, UVC_GET_MAX,
-				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_MAX));
-	else
-		v4l2_ctrl->maximum = 0;
+	v4l2_ctrl->maximum =
+		uvc_queryctrl_single_boundary(chain, ctrl, mapping,
+					      UVC_GET_MAX);
 
-	if (ctrl->info.flags & UVC_CTRL_FLAG_GET_RES)
-		v4l2_ctrl->step = uvc_mapping_get_s32(mapping, UVC_GET_RES,
-				uvc_ctrl_data(ctrl, UVC_CTRL_DATA_RES));
-	else
-		v4l2_ctrl->step = 0;
+	v4l2_ctrl->step =
+		uvc_queryctrl_single_boundary(chain, ctrl, mapping,
+					      UVC_GET_RES);
 
 	return 0;
 }

-- 
2.51.0.536.g15c5d4f767-goog