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

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