Re: [PATCH 1/3] serial: 8250_early: Add earlycon support for AMD Carrizo / Stoneyridge

[Andy Shevchenko]

On Wed, Mar 14, 2018 at 6:29 PM, Daniel Kurtz <djkurtz@xxxxxxxxxxxx> wrote:
> On Wed, Mar 14, 2018 at 4:54 AM Ricardo Ribalda Delgado <
> ricardo.ribalda@xxxxxxxxx> wrote:
>> On Wed, Mar 14, 2018 at 1:36 AM, Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
> wrote:

> In fact, the recommended way is to have firmware specify an ACPI SPCR table
> with OEMID="AMDCZ " (see https://patchwork.kernel.org/patch/10281307/) to
> configure proper access and address.

Hmm... I was thinking it's already there. And thus, this is just a
quirk for *existing* firmware that doesn't correctly configured
hardware.
(Yes, I'm aware about one nuance in SPCR specification I'm trying to
address via official ways)

>  With an SPCR table in place,  the
> kernel command line just becomes "earlycon", with no parameters.

SPCR *provides* an address of UART (required by specification).

-- 
With Best Regards,
Andy Shevchenko