V4L/DVB (9810): uvcvideo: Add a device quirk to prune bogus controls.

Bogus controls currently include processing unit auto controls for which no
corresponding manual control is available. Such auto controls make little
sense if any, and are known to crash at least the SiGma Micro webcam.

Signed-off-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/video/uvc/uvc_ctrl.c

···
 	return ctrl->data + id * ctrl->info->size;
 }
 
-static inline int uvc_get_bit(const __u8 *data, int bit)
+static inline int uvc_test_bit(const __u8 *data, int bit)
 {
 	return (data[bit >> 3] >> (bit & 7)) & 1;
+}
+
+static inline void uvc_clear_bit(__u8 *data, int bit)
+{
+	data[bit >> 3] &= ~(1 << (bit & 7));
 }
 
 /* Extract the bit string specified by mapping->offset and mapping->size
···
 }
 
 /*
+ * Prune an entity of its bogus controls. This currently includes processing
+ * unit auto controls for which no corresponding manual control is available.
+ * Such auto controls make little sense if any, and are known to crash at
+ * least the SiGma Micro webcam.
+ */
+static void
+uvc_ctrl_prune_entity(struct uvc_entity *entity)
+{
+	static const struct {
+		u8 idx_manual;
+		u8 idx_auto;
+	} blacklist[] = {
+		{ 2, 11 }, /* Hue */
+		{ 6, 12 }, /* White Balance Temperature */
+		{ 7, 13 }, /* White Balance Component */
+	};
+
+	u8 *controls;
+	unsigned int size;
+	unsigned int i;
+
+	if (UVC_ENTITY_TYPE(entity) != VC_PROCESSING_UNIT)
+		return;
+
+	controls = entity->processing.bmControls;
+	size = entity->processing.bControlSize;
+
+	for (i = 0; i < ARRAY_SIZE(blacklist); ++i) {
+		if (blacklist[i].idx_auto >= 8 * size ||
+		    blacklist[i].idx_manual >= 8 * size)
+			continue;
+
+		if (!uvc_test_bit(controls, blacklist[i].idx_auto) ||
+		     uvc_test_bit(controls, blacklist[i].idx_manual))
+			continue;
+
+		uvc_trace(UVC_TRACE_CONTROL, "Auto control %u/%u has no "
+			"matching manual control, removing it.\n", entity->id,
+			blacklist[i].idx_auto);
+
+		uvc_clear_bit(controls, blacklist[i].idx_auto);
+	}
+}
+
+/*
  * Initialize device controls.
  */
 int uvc_ctrl_init_device(struct uvc_device *dev)
···
 			bControlSize = entity->camera.bControlSize;
 		}
 
+		if (dev->quirks & UVC_QUIRK_PRUNE_CONTROLS)
+			uvc_ctrl_prune_entity(entity);
+
 		for (i = 0; i < bControlSize; ++i)
 			ncontrols += hweight8(bmControls[i]);
 
···
 
 		ctrl = entity->controls;
 		for (i = 0; i < bControlSize * 8; ++i) {
-			if (uvc_get_bit(bmControls, i) == 0)
+			if (uvc_test_bit(bmControls, i) == 0)
 				continue;
 
 			ctrl->entity = entity;

drivers/media/video/uvc/uvc_driver.c

···
 	  .bInterfaceSubClass	= 1,
 	  .bInterfaceProtocol	= 0,
 	  .driver_info		= UVC_QUIRK_PROBE_MINMAX
-				| UVC_QUIRK_IGNORE_SELECTOR_UNIT},
+				| UVC_QUIRK_IGNORE_SELECTOR_UNIT
+				| UVC_QUIRK_PRUNE_CONTROLS },
 	/* Generic USB Video Class */
 	{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, 0) },
 	{}

drivers/media/video/uvc/uvcvideo.h

···
 #define UVC_QUIRK_BUILTIN_ISIGHT	0x00000008
 #define UVC_QUIRK_STREAM_NO_FID		0x00000010
 #define UVC_QUIRK_IGNORE_SELECTOR_UNIT	0x00000020
+#define UVC_QUIRK_PRUNE_CONTROLS	0x00000040
 
 /* Format flags */
 #define UVC_FMT_FLAG_COMPRESSED		0x00000001