[PATCH 1/2] kernel: usb: Autoprobe g_serial

[Lech Perczak]

Hi Linus,

W dniu 2023-11-11 o 23:02, Linus Walleij pisze:
> For devices using USB gadget serial we need to probe the modules
> usb_f_acm and g_serial in order, then the available UDC (USB device
> controller) interface will be hooked up to a serial port as
> /dev/ttyGS0. (On the host side this appears as /dev/ttyACM0
> when plugging in the USB cable.)
>
> I don't quite understand why this wasn't done before for the
> module explicitly called kmod-usb-serial.
>
> Before this patch we have to enter a console and type
>
>    modprobe g_serial
>
> To get a serial console on /dev/ttyGS0, after this it is
> automatic.
>
> Since you might only have the serial console, it is a bit
> catch 22 to have to use a serial console to activate the
> serial console.
>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
> ---
>   package/kernel/linux/modules/usb.mk | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/package/kernel/linux/modules/usb.mk b/package/kernel/linux/modules/usb.mk
> index 0a5f5a8993c9..f54dc4380737 100644
> --- a/package/kernel/linux/modules/usb.mk
> +++ b/package/kernel/linux/modules/usb.mk
> @@ -207,7 +207,7 @@ define KernelPackage/usb-gadget-serial
>   	$(LINUX_DIR)/drivers/usb/gadget/function/usb_f_obex.ko \
>   	$(LINUX_DIR)/drivers/usb/gadget/function/usb_f_serial.ko \
>   	$(LINUX_DIR)/drivers/usb/gadget/legacy/g_serial.ko
> -  AUTOLOAD:=$(call AutoLoad,52,usb_f_acm)
> +  AUTOLOAD:=$(call AutoLoad,52,usb_f_acm g_serial)
>     $(call AddDepends/usb)
>   endef
>   
>
I think I know the reason why it isn't the case. 
kmod-usb-gadget-cdc-composite which pulls both kmod-usb-gadget-serial 
and kmod-usb-gadget-eth packages, and including autoprobingf g_serial 
within this would clash with that. I think the gadget configuration 
itself (apart from implementation) could be packaged separately and 
included as device packages, pulling needed dependencies. And something 
like that just appeared on Github: 
https://github.com/openwrt/openwrt/pull/14005/

-- 
Pozdrawiam/Kind regards,
Lech