UDC core dependent of CONFIG_MODULES?

UDC core dependent of CONFIG_MODULES?

[deffo]

Hi all,

is the UDC core meant to be used only with CONFIG_MODULES=y? Because I have the problem, that I want to configure g_ether via CONFIGFS, but when I do

ls /sys/class/udc/ > /sys/kernel/config/usb_gadget/g/UDC

in order to enable the gadget, I get the error:

[ 314.569798] udc-core: couldn't find an available UDC or it's busy

Sure g_ether is already enabled via UDC and as such cannot be configured anymore:

[ 9.981767] udc 49000000.usb-otg: registering UDC driver [g_ether]

Trying to disable UDC via:

echo "" > /sys/kernel/config/usb_gadget/UDC

won't help either. Am I forced to use modules here? Or am I doing something wrong?

Bye,
Joe

Re: UDC core dependent of CONFIG_MODULES?

[Alan Stern]

On Fri, Mar 17, 2023 at 01:08:43PM +0100, deffo@gmx.de wrote:
> Hi all,
> 
> is the UDC core meant to be used only with CONFIG_MODULES=y? Because I 
> have the problem, that I want to configure g_ether via CONFIGFS, but 
> when I do
> 
> ls /sys/class/udc/ > /sys/kernel/config/usb_gadget/g/UDC
> 
> in order to enable the gadget, I get the error:
> 
> [ 314.569798] udc-core: couldn't find an available UDC or it's busy
> 
> Sure g_ether is already enabled via UDC and as such cannot be 
> configured anymore:
> 
> [ 9.981767] udc 49000000.usb-otg: registering UDC driver [g_ether]
> 
> Trying to disable UDC via:
> 
> echo "" > /sys/kernel/config/usb_gadget/UDC
> 
> won't help either. Am I forced to use modules here? Or am I doing 
> something wrong?

Provided your kernel version is 5.19 or later, you can unbind the UDC 
from the g_ether driver via sysfs:

	echo 49000000.usb-otg >/sys/bus/gadget/drivers/g_ether/unbind

(or something like that).  Once you do that, it should be possible to 
configure your gadget using configfs.

Alan Stern