Re: [PATCH 1/2] serial: 8250: enable SERIAL_MCTRL_GPIO by default.

[Andy Shevchenko]

On Mon, 2018-06-04 at 20:57 +0200, Giulio Benetti wrote:
> Il 04/06/2018 13:49, Andy Shevchenko ha scritto:
> > On Fri, 2018-06-01 at 16:11 +0200, Giulio Benetti wrote:
> > > It can be useful to override 8250 mctrl lines with gpios, for rts
> > > on
> > > rs485 for example, when rts is not mapped correctly to HW RTS pin.
> > > 
> > > Enable SERIAL_MCTRL_GPIO by default.
> > > 
> > 
> > Unfortunately NAK, see
> > 
> > commit 5db4f7f80d165fc9725f356e99feec409e446baa
> > Author: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Date:   Tue Aug 16 15:06:54 2016 +0300
> > 
> >      Revert "tty/serial/8250: use mctrl_gpio helpers"
> > 
> > for the details.
> > 
> > I would love to see a solution that will satisfy everyone, though I
> > have
> > only means to test proposals for now.
> 
> Thanks for pointing me that.
> I would try to solve serial breakage on intel with already extisting 
> patches dropping this one.
> I'm going to try.
> 
> I can't understand if it's enough using qemu x86 to reproduce the bug.
> If so I'm going to debug and check what makes driver to fail.

You need to provide an ACPI table with UART contains GpioInt() or
GpioIo() resource in it.

Where GPIO number is a number of pin related to UART's RxD.


> Do you think it makes sense? Would it be accepted after bug fixing?

I can test on our hardware. Can't say about the rest, though.

-- 
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy