Re: [PATCH v6] serial: rewrite pxa2xx-uart to use 8250_core

Sergei Ianovich
2016-02-22T01:56:38Z

On Sat, 2016-02-06 at 22:22 -0800, Greg Kroah-Hartman wrote:
> On Thu, Dec 24, 2015 at 06:15:14PM +0300, Sergei Ianovich wrote:
> > pxa2xx-uart was a separate uart platform driver. It was declaring
> > the same device names and numbers as 8250 driver. As a result,
> > it was impossible to use 8250 driver on PXA SoCs.
> >
> > Upon closer examination pxa2xx-uart turned out to be a clone of
> > 8250_core driver.
> >
> > Workaround for Erratum #19 according to Marvel(R) PXA270M Processor
> > Specification Update (April 19, 2010) is dropped. 8250_core reads
> > from FIFO immediately after checking DR bit in LSR.
> >
> > The patch leaves the original SERIAL_PXA driver around. The
> > original
> > driver is just marked DEPRECATED in Kconfig and C source. When
> > the original driver is considered safe to remove, no changes
> > to SERIAL_8250 will be necessary.
>
> But, you just broke existing configurations, right?  The serial port is
> a different name now, are you willing to handle the angry users?

No, the port name remains /dev/ttyS0. In fact, this conflict (both
drivers use the same name and char major) is the reason for the patch.
Noone should notice the change at runtime. There will be a warning at
compile time which should make the transition to the new driver faster.

> If so, great, get the platform maintainer to sign off on this please and
> then resend it.

The previous version of the patch has been around for 2 years with half
a dozen of Acks and Reviews, but it hasn't landed. Could you suggest a
better approach?

--
Sergei Ianovich <ynvich@gmail.com>