Re: [PATCH v5 1/1] usb: gadget: add raw-gadget interface

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Jan 14, 2020 at 02:24:43PM +0100, Andrey Konovalov wrote:
> USB Raw Gadget is a kernel module that provides a userspace interface for
> the USB Gadget subsystem. Essentially it allows to emulate USB devices
> from userspace. Enabled with CONFIG_USB_RAW_GADGET. Raw Gadget is
> currently a strictly debugging feature and shouldn't be used in
> production.
> 
> Raw Gadget is similar to GadgetFS, but provides a more low-level and
> direct access to the USB Gadget layer for the userspace. The key
> differences are:
> 
> 1. Every USB request is passed to the userspace to get a response, while
>    GadgetFS responds to some USB requests internally based on the provided
>    descriptors. However note, that the UDC driver might respond to some
>    requests on its own and never forward them to the Gadget layer.
> 
> 2. GadgetFS performs some sanity checks on the provided USB descriptors,
>    while Raw Gadget allows you to provide arbitrary data as responses to
>    USB requests.
> 
> 3. Raw Gadget provides a way to select a UDC device/driver to bind to,
>    while GadgetFS currently binds to the first available UDC.
> 
> 4. Raw Gadget uses predictable endpoint names (handles) across different
>    UDCs (as long as UDCs have enough endpoints of each required transfer
>    type).
> 
> 5. Raw Gadget has ioctl-based interface instead of a filesystem-based one.
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
> 
> Greg, I've assumed your LGTM meant that I can add a Reviewed-by from you.

Yes, I was about to give it a "real" one, but that is fine here, thanks.

greg k-h