Am Donnerstag, den 05.04.2018, 08:26 +0200 schrieb Greg KH:
> > The USB device can describe itself properly.  The SMBIOS function is a
> > requirement from our customer who designed a board using our device where
> > their CPU reads from a specific BIOS location and initializes GPIOs based
> > on the settings.  These GPIOs set the mode of the transceiver (LOOPBACK,
> > RS232, RS485, or RS422).  Therefore, the driver also reads the same
> > settings from the BIOS, so that it can enable the appropriate mode.
> That logic can be done in userspace, no need to do that within the
> kernel, right?

No, not if you want to do full RS485 and similar stuff.

Yet ACM is not a full serial interface. It is for modems.
That raises two questions

a) why not add this to cdc-acm?
b) why custom ioctls? The kernel can do those serial protocols at upper


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