Re: [PATCH] serial: core: Fix probing serial_base_bus devices

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Jun 01, 2023 at 06:07:06PM +0300, Tony Lindgren wrote:
> * Greg Kroah-Hartman <gregkh@linuxfoundation.org> [230601 14:21]:
> > On Thu, Jun 01, 2023 at 05:14:44PM +0300, Tony Lindgren wrote:
> > > If a physical serial port device driver uses arch_initcall() we fail to
> > > probe the serial_base_bus devices and the serial port tx fails. This is
> > > because as serial_base_bus uses module_initcall().
> > > 
> > > Let's fix the issue by changing serial_base_bus to use arch_initcall().
> > 
> > This will only work if the linking order is such that this will always
> > come before the drivers.  Is that the case here?
> 
> I guess based on Makefile. And also if serial drivers are modules as we
> export uart_add_one_port() from serial_base.ko. But yeah this is pretty
> fragile potentially.

It's fine, and normal, the Makefile is the ordering here so all is good.

> Hmm maybe we could keep module_init() and then also call serial_base_init()
> on uart_add_one_port() path if not yet initialized?
> 
> Probably the module_init() should be still there for case when no serial
> port device drivers are loaded and serial_base is unloaded..

I'll leave this as-is, it looks correct, and I'll queue it up now,
thanks.

greg k-h