[U-Boot] [PATCH 1/1] serial: ns16550: Read reg-io-type from device tree

[Bin Meng]

Hi Aiden,

On Thu, Aug 22, 2019 at 12:40 AM Park, Aiden <aiden.park at intel.com> wrote:
>
> Hi Andy/Bin,
>
> > -----Original Message-----
> > From: Bin Meng [mailto:bmeng.cn at gmail.com]
> > Sent: Wednesday, August 21, 2019 2:45 AM
> > To: Andy Shevchenko <andy.shevchenko at gmail.com>
> > Cc: Park, Aiden <aiden.park at intel.com>; u-boot at lists.denx.de
> > Subject: Re: [U-Boot] [PATCH 1/1] serial: ns16550: Read reg-io-type from
> > device tree
> >
> > On Wed, Aug 21, 2019 at 3:26 PM Andy Shevchenko
> > <andy.shevchenko at gmail.com> wrote:
> > >
> > > On Wed, Aug 21, 2019 at 3:43 AM Park, Aiden <aiden.park at intel.com>
> > wrote:
> > > >
> > > > ns16550 can select register access type from device tree.
> > > > This also allows an inherited serial driver of ns16550 to configure
> > > > register access type at run-time by overriding ofdata_to_platdata.
> > > >
> > >
> > > Can you elaborate more on this?
> > >
> > > For now it looks like a hack due to misunderstanding of the design.
> >
> Right, this is a just hack. As Bin said, we may need refactor whole codes.
> By the way, do we need to keep current design which selects I/O port or MMIO
> at compile time by defining CONFIG_SYS_NS16550_PORT_MAPPED
> or CONFIG_SYS_NS16550_MEM32?

I think we should drop these 2 config options, and refactor the whole
16550 driver, eg: porting the Linux 8250 driver to U-Boot.

>
> > The reg-io-type is not a standard DTS property for 8250
> > (Documentation/devicetree/bindings/serial/8250.txt) so I guess we may
> > need refactor the ns16550 codes to support both I/O port and memory-
> > mapped variants.
> >
> Thanks for letting me know 8250.txt(doc/device-tree-bindings/serial/8250.txt).
> I agree that ns16550 codes may need refactor. Let me abandon this patch.

Regards,
Bin