Re: [PATCH 1/2] serial: 8250: Allow port registration without UPF_BOOT_AUTOCONF

Andy Shevchenko
2019-04-26T21:51:11Z

On Fri, Apr 26, 2019 at 06:54:05PM +0200, Esben Haabendal wrote:
> Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
> > On Fri, Apr 26, 2019 at 10:40:37AM +0200, Esben Haabendal wrote:
> >> With serial8250_register_8250_port() forcing UPF_BOOT_AUTOCONF bit on, it
> >> is not possible to register a port without having
> >> serial8250_request_std_resource() called.
> >>
> >> For adding a 8250 port to an MFD device, this is problematic, as the
> >> request_mem_region() call will fail, as the MFD device (and rightly so)
> >> has requested the region. For this case, the 8250 port should accept
> >> having passed mapbase and membase, and just use that.
> >
> > You need to simple set port type and use UPF_FIXED_TYPE.
> > No need for this patch.
>
> The reason for this patch is to be able to do exactly that (set port
> type and UPF_FIXED_TYPE) without having UPF_BOOT_AUTOCONF added.
>
> In the current serial8250_register_8250_port() there is:
>
> uart->port.flags = up->port.flags | UPF_BOOT_AUTOCONF;
>
> So, even though I set UPF_FIXED_TYPE, I get
> UPF_FIXED_TYPE|UPF_BOOT_AUTOCONF.

Yes.

> So I need this patch.

Why? I don't see any problems to have these flags set. Moreover, some drivers
are used as MFD counterparts with exactly same bits set.

> I think it is unfortunate that UPF_BOOT_AUTOCONF is or'ed to flags like
> that, but changing that will surely break stuff.

True.

--
With Best Regards,
Andy Shevchenko