8 +165,17 @@ static struct uvc_entity *uvc_entity_by_reference(struct uvc_device *dev,
 	return NULL;
 }
 
-static struct uvc_streaming *uvc_stream_by_id(struct uvc_device *dev, int id)
+static struct uvc_streaming *uvc_stream_for_terminal(struct uvc_device *dev,
+						     struct uvc_entity *term)
 {
-	struct uvc_streaming *stream, *last_stream;
-	unsigned int count = 0;
+	u16 id = UVC_HARDWARE_ENTITY_ID(term->id);
+	struct uvc_streaming *stream;
 
 	list_for_each_entry(stream, &dev->streams, list) {
-		count += 1;
-		last_stream = stream;
 		if (stream->header.bTerminalLink == id)
 			return stream;
 	}
 
-	/*
-	 * If the streaming entity is referenced by an invalid ID, notify the
-	 * user and use heuristics to guess the correct entity.
-	 */
-	if (count == 1 && id == UVC_INVALID_ENTITY_ID) {
-		dev_warn(&dev->intf->dev,
-			 "UVC non compliance: Invalid USB header. The streaming entity has an invalid ID, guessing the correct one.");
-		return last_stream;
-	}
-
 	return NULL;
 }
 
@@ -823,10 +812,12 @@ static struct uvc_entity *uvc_alloc_new_entity(struct uvc_device *dev, u16 type,
 	}
 
 	/* Per UVC 1.1+ spec 3.7.2, the ID is unique. */
-	if (uvc_entity_by_id(dev, id)) {
-		dev_err(&dev->intf->dev, "Found multiple Units with ID %u\n", id);
+	if (uvc_entity_by_id(dev, UVC_HARDWARE_ENTITY_ID(id)))
+		dev_err(&dev->intf->dev, "Found multiple Units with ID %u\n",
+			UVC_HARDWARE_ENTITY_ID(id));
+
+	if (uvc_entity_by_id(dev, id))
 		id = UVC_INVALID_ENTITY_ID;
-	}
 
 	extra_size = roundup(extra_size, sizeof(*entity->pads));
 	if (num_pads)
@@ -982,6 +973,7 @@ static int uvc_parse_standard_control(struct uvc_device *dev,
 	struct usb_host_interface *alts = dev->intf->cur_altsetting;
 	unsigned int i, n, p, len;
 	const char *type_name;
+	unsigned int id;
 	u16 type;
 
 	switch (buffer[2]) {
@@ -1120,8 +1112,28 @@ static int uvc_parse_standard_control(struct uvc_device *dev,
 			return 0;
 		}
 
+		id = buffer[3];
+
+		/*
+		 * Some devices, such as the Grandstream GUV3100, exhibit entity
+		 * ID collisions between units and streaming output terminals.
+		 * Move streaming output terminals to their own ID namespace by
+		 * setting bit UVC_TERM_OUTPUT (15), above the ID's 8-bit value.
+		 * The bit is ignored in uvc_stream_for_terminal() when looking
+		 * up the streaming interface for the terminal.
+		 *
+		 * This hack is safe to enable unconditionally, as the ID is not
+		 * used for any other purpose (streaming output terminals have
+		 * no controls and are never referenced as sources in UVC
+		 * descriptors). Other types output terminals can have controls,
+		 * so limit usage of this separate namespace to streaming output
+		 * terminals.
+		 */
+		if (type & UVC_TT_STREAMING)
+			id |= UVC_TERM_OUTPUT;
+
 		term = uvc_alloc_new_entity(dev, type | UVC_TERM_OUTPUT,
-					    buffer[3], 1, 0);
+					    id, 1, 0);
 		if (IS_ERR(term))
 			return PTR_ERR(term);
 
@@ -2118,8 +2130,8 @@ static int uvc_register_terms(struct uvc_device *dev,
 		if (UVC_ENTITY_TYPE(term) != UVC_TT_STREAMING)
 			continue;
 
-		stream = uvc_stream_by_id(dev, term->id);
-		if (stream == NULL) {
+		stream = uvc_stream_for_terminal(dev, term);
+		if (!stream) {
 			dev_info(&dev->intf->dev,
 				 "No streaming interface found for terminal %u.",
 				 term->id);
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index ed7bad31f75ca..3f2e832025e71 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -41,7 +41,8 @@
 #define UVC_EXT_GPIO_UNIT		0x7ffe
 #define UVC_EXT_GPIO_UNIT_ID		0x100
 
-#define UVC_INVALID_ENTITY_ID          0xffff
+#define UVC_HARDWARE_ENTITY_ID(id)	((id) & 0xff)
+#define UVC_INVALID_ENTITY_ID		0xffff
 
 /* ------------------------------------------------------------------------
  * Driver specific constants.
-- 
2.51.0[PATCH 6.19 213/844] media: uvcvideo: Create an ID namespace for streaming output terminalsSasha Levin <sashal@kernel.org> undefinedlinux-kernel@vger.kernel.org, stable@vger.kernel.org undefined undefined undefined undefined undefined undefined