uvcvideo: Add a device quirk to prune bogus controls.

From: Laurent Pinchart <laurent.pinchart@skynet.be>

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.

Priority: normal

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>

1 files changed, 55 insertions, 2 deletions

diff --git a/linux/drivers/media/video/uvc/uvc_ctrl.c b/linux/drivers/media/video/uvc/uvc_ctrl.c
index 9de8a1db5..01c72935d 100644
--- a/linux/drivers/media/video/uvc/uvc_ctrl.c
+++ b/linux/drivers/media/video/uvc/uvc_ctrl.c
@@ -545,11 +545,16 @@ static inline __u8 *uvc_ctrl_data(struct uvc_control *ctrl, int id)
 	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
  * from the little-endian data stored at 'data' and return the result as
  * a signed 32bit integer. Sign extension will be performed if the mapping
@@ -1308,6 +1313,51 @@ end:
 }
 
 /*
+ * 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)
@@ -1333,6 +1383,9 @@ 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]);
 
@@ -1347,7 +1400,7 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
 
 		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;