[v5,1/2] usb/gadget/uvc-configs Fix host unable to negotiate framesizes other than first

[Felipe Balbi <balbi@kernel.org>]

Hi,

Joel Pepper <joel.pepper@rwth-aachen.de> writes:
> - 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
>
> v4: Actually include updated patch
>
> v5: bFrameIndex now returns -EBUSY if the parent fmt is not linked yet
>
> Signed-off-by: Joel Pepper <joel.pepper@rwth-aachen.de>

no Ack from Laurent yet? hmm, I'll have to delay this one for the next
merge window, sorry. Just as a side note, version changes (v2, v3, v4,
v5 above) should comer after the tearline (---) below. We don't need
these changes in the commit log, it's just for maintainers to read :-)

If we had an ack from Laurent, I'd fix that while applying, but since
you're gonna have to resend anyway, please fix that once we get an Ack
from Laurent.