[2/2] usb: gadget: uvc: configfs: Add bFrameIndex attributes

From: Paul Elder <paul.elder@ideasonboard.com>

The UVC frame descriptions are numbered using the descriptor's
bFrameIndex field. The index is used in UVC requests, and is thus
needed to handle requests in userspace. Make it dynamically discoverable
by exposing it in a bFrameIndex configfs attribute of the frame
config item.

However, the bFrameIndex value is never set to begin with. Set these
values when linking the stream class header in the configfs hierarchy,
and store it in the config item private data.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
---
 drivers/usb/gadget/function/uvc_configfs.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/uvc_configfs.c

b/drivers/usb/gadget/function/uvc_configfs.c index
0ad6ea57d0b7..882d9963b244 100644

--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c

@@ -1152,6 +1152,8 @@ UVC_ATTR(uvcg_frame_, cname, aname);

 #define noop_conversion(x) (x)

+UVCG_FRAME_ATTR_RO(b_frame_index, bFrameIndex, noop_conversion,
+		noop_conversion, 8);
 UVCG_FRAME_ATTR(bm_capabilities, bmCapabilities, noop_conversion,
 		noop_conversion, 8);
 UVCG_FRAME_ATTR(w_width, wWidth, le16_to_cpu, cpu_to_le16, 16);

@@ -1298,6 +1300,7 @@ static ssize_t

uvcg_frame_dw_frame_interval_store(struct config_item *item,
UVC_ATTR(uvcg_frame_, dw_frame_interval, dwFrameInterval);

 static struct configfs_attribute *uvcg_frame_attrs[] = {
+	&uvcg_frame_attr_b_frame_index,
 	&uvcg_frame_attr_bm_capabilities,
 	&uvcg_frame_attr_w_width,
 	&uvcg_frame_attr_w_height,

@@ -2130,12 +2133,15 @@ static int __uvcg_fill_strm(void *priv1, void

*priv2, void *priv3, int n, sizeof(*frm->dw_frame_interval);
 		memcpy(*dest, frm->dw_frame_interval, sz);
 		*dest += sz;
-		if (frm->fmt_type == UVCG_UNCOMPRESSED)
+		if (frm->fmt_type == UVCG_UNCOMPRESSED) {
 			h->bLength = UVC_DT_FRAME_UNCOMPRESSED_SIZE(
 				frm->frame.b_frame_interval_type);
-		else if (frm->fmt_type == UVCG_MJPEG)
+			frm->frame.b_frame_index = n + 1;
+		} else if (frm->fmt_type == UVCG_MJPEG) {
 			h->bLength = UVC_DT_FRAME_MJPEG_SIZE(
 				frm->frame.b_frame_interval_type);
+			frm->frame.b_frame_index = n + 1;
+		}
 	}
 	break;
 	}