Re: [PATCH 0/3] USB-Serial serdev support

Marco Felsch
2025-03-03T11:25:39Z

Hi,

On 24-10-28, Marco Felsch wrote:
> Hi Greg,
>
> On 24-10-01, Greg Kroah-Hartman wrote:
> > On Tue, Oct 01, 2024 at 09:24:53AM +0200, Marco Felsch wrote:
> > > Hi,
> > >
> > > gentle ping as this is series is two months old now.
> >
> > And it was rejected as serdev does not support hotplug which of course,
> > usb-serial does.
>
> I hoped to get some feedback on my answer [1]. Regarding hotplug
> support: serdev _requires_ some sort of firmware like OF (not sure if it
> does work with ACPI too). That said, if serdev finds no firmware a
> fallback is provided to the standard serial handling.
>
> The firmware could either be added directly by the platform OF file or
> via OF-overlays. By making use of overlays we could gain some kind of
> hotplug: Once a usb devices was detected and the driver has an
> overlay, the overlay gets applied and the probe continues, like we do it
> for PCIe devices now [2]. For devices which don't have a registered
> overlay the standard usb-serial setup is done by exposing the serial
> interface to the userspace.

is this idea worth to give it a try for a v2 or do you have something
different in mind?

I'm happy for any input.

Regards,
Marco

> > So until serdev is fixed up to handle that correctly, this is not going
> > anywhere, nor should you want it to as then you would be in charge of
> > code that does not work properly :)
>
> Regards,
> Marco
>
> [1] https://lore.kernel.org/all/20240917044948.i2eog4ondf7vna7q@pengutronix.de/
> [2] https://lore.kernel.org/all/7512cbb7911b8395d926e9e9e390fbb55ce3aea9.camel@pengutronix.de/
>
> >
> > thanks,
> >
> > greg k-h
> >