usb/gadget/uvc-configs Fix host unable to negotiate framesizes other than first

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Joel,

Thank you for the patch.

On Tuesday, 20 March 2018 22:28:53 EET Joel Pepper wrote:
> - 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.
> 
> v2: Add the new attribute to both MJPEG and uncompressed frame descriptors
> in Documentation/ABI, with note that it was added only in a later
> kernel version
> 
> v3: Changed from simply allowing user to set the value for bFrameIndex to
> automatically assigning correct distinct frame indexes. Changed
> bFrameIndex from RW to RO

I like the new commit message, but it would be nice if you could also update 
the patch contents ;-)

(By the way the subject line should have mentioned "[PATCH v3]")

> Signed-off-by: Joel Pepper <joel.pepper@rwth-aachen.de>
> ---
>  Documentation/ABI/testing/configfs-usb-gadget-uvc | 17 +++++++++++++++++
>  drivers/usb/gadget/function/uvc_configfs.c        |  3 +++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc
> b/Documentation/ABI/testing/configfs-usb-gadget-uvc index 1ba0d0f..d435cf7
> 100644
> --- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
> +++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
> @@ -194,6 +194,14 @@ Description:	Specific MJPEG frame descriptors
>  		bmCapabilities		- still image support, fixed frame-rate
>  					support
> 
> +Date:		Mar 2018
> +KernelVersion:	4.16
> +
> +		bFrameIndex		- unique id for this framedescriptor;
> +					if using multiple framedescriptors for
> +					same format, user needs to set distinct
> +					value for each frame descriptor
> +
>  What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/
uncompressed
>  Date:		Dec 2014
>  KernelVersion:	4.0
> @@ -241,6 +249,15 @@ Description:	Specific uncompressed frame descriptors
>  		bmCapabilities		- still image support, fixed frame-rate
>  					support
> 
> +Date:           Mar 2018
> +KernelVersion:  4.16
> +
> +                bFrameIndex             - unique id for this
> framedescriptor; +                                        if using multiple
> framedescriptors for +                                        same format,
> user needs to set distinct +                                        value
> for each frame descriptor +
> +
>  What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/header
>  Date:		Dec 2014
>  KernelVersion:	4.0
> diff --git a/drivers/usb/gadget/function/uvc_configfs.c
> b/drivers/usb/gadget/function/uvc_configfs.c index c9b8cc4a..5966d65 100644
> --- a/drivers/usb/gadget/function/uvc_configfs.c
> +++ b/drivers/usb/gadget/function/uvc_configfs.c
> @@ -992,6 +992,8 @@ UVC_ATTR(uvcg_frame_, cname, aname);
> 
>  UVCG_FRAME_ATTR(bm_capabilities, bmCapabilities, noop_conversion,
>  		noop_conversion, 8);
> +UVCG_FRAME_ATTR(b_frame_index, bFrameIndex, noop_conversion,
> +		noop_conversion, 8);
>  UVCG_FRAME_ATTR(w_width, wWidth, le16_to_cpu, cpu_to_le16, 16);
>  UVCG_FRAME_ATTR(w_height, wHeight, le16_to_cpu, cpu_to_le16, 16);
>  UVCG_FRAME_ATTR(dw_min_bit_rate, dwMinBitRate, le32_to_cpu, cpu_to_le32,
> 32); @@ -1137,6 +1139,7 @@ UVC_ATTR(uvcg_frame_, dw_frame_interval,
> dwFrameInterval);
> 
>  static struct configfs_attribute *uvcg_frame_attrs[] = {
>  	&uvcg_frame_attr_bm_capabilities,
> +	&uvcg_frame_attr_b_frame_index,
>  	&uvcg_frame_attr_w_width,
>  	&uvcg_frame_attr_w_height,
>  	&uvcg_frame_attr_dw_min_bit_rate,