usb: gadget: uvc: configfs: Add bFrameIndex attributes

From
Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date
2018-06-08 19:53:35 
From: Joel Pepper <redacted>

- Add bFrameIndex as a UVCG_FRAME_ATTR_RO for each frame size.
- Automatically assign ascending bFrameIndex to each frame in a format.

Before all "bFrameindex" attributes were set to "1" with no way to
configure the gadget otherwise. This resulted in the host always
negotiating for bFrameIndex 1 (i.e. the first framesize of the gadget).
After the negotiation the host driver will set the user or application
selected framesize, while the gadget is actually set to the first
framesize.

Now, when the containing format is linked into the streaming header,
iterate over all child frame descriptors and assign ascending indices.
The automatically assigned indices can be read from the new read only
bFrameIndex configsfs attribute in each frame descriptor item.

Signed-off-by: Joel Pepper <redacted>
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
[Merge Joel's documentation and Paul's code]
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 Documentation/ABI/testing/configfs-usb-gadget-uvc |  8 ++++++++
 drivers/usb/gadget/function/uvc_configfs.c        | 10 ++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

This is the mix of Paul's and Joel's patches. I've also simplified the
ABI documentation by omitting the changelog date and kernel version as
seems to be the common practice when adding new attributes to existing
directories.

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc b/Documentation/ABI/testing/configfs-usb-gadget-uvc
index 9281e2aa38df..bee6ab72e6b1 100644
--- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
+++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
@@ -177,6 +177,10 @@ Date:		Dec 2014
 KernelVersion:	4.0
 Description:	Specific MJPEG frame descriptors
 
+		bFrameIndex		- unique id for this framedescriptor;
+					only defined after parent format is
+					linked into the streaming header;
+					read-only
 		dwFrameInterval		- indicates how frame interval can be
 					programmed; a number of values
 					separated by newline can be specified
@@ -224,6 +228,10 @@ Date:		Dec 2014
 KernelVersion:	4.0
 Description:	Specific uncompressed frame descriptors
 
+		bFrameIndex		- unique id for this framedescriptor;
+					only defined after parent format is
+					linked into the streaming header;
+					read-only
 		dwFrameInterval		- indicates how frame interval can be
 					programmed; a number of values
 					separated by newline can be specified
diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
index 1122659ccfe6..1645be415933 100644
--- a/drivers/usb/gadget/function/uvc_configfs.c
+++ b/drivers/usb/gadget/function/uvc_configfs.c
@@ -1155,6 +1155,8 @@ 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);
@@ -1301,6 +1303,7 @@ 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,
@@ -2133,12 +2136,15 @@ 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;
 	}
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