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From:   Aaron Durbin <adurbin@chromium.org>
Date:   Mon, 9 Apr 2018 10:00:13 -0600
Message-ID: <CAE2855vVXr24bOjXvU7pVcDs_X-6G-xndsUf=9jtyXVJS5G6bA@mail.gmail.com>
Subject: Re: [PATCH 1/3] serial: 8250_early: Add earlycon support for AMD
 Carrizo / Stoneyridge
To:     Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc:     Aaron Durbin <adurbin@chromium.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Daniel Kurtz <djkurtz@chromium.org>,
        Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>,
        Marc Gonzalez <marc_gonzalez@sigmadesigns.com>,
        Doug Anderson <dianders@chromium.org>,
        Matt Redfearn <matt.redfearn@mips.com>,
        Jeffy <jeffy.chen@rock-chips.com>,
        "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Apr 6, 2018 at 7:47 AM, Alan Cox <gnomes@lxorguk.ukuu.org.uk> wrote:
>> But we don't have the full ACPI interpreter up in the early part of
>> the kernel. All these 'early' devices have their own setup/config
>> which is the source of the issue. Or maybe I am wrong about the full
>> interpreter and the early drivers are just not taking advantage of the
>> ACPI device binding?
>
> In very early boot with serial console you just have to pray. No change
> there. Once ACPI comes up you however have the information to populate
> everything and configure correctly.
>
> So it should work fine except for kernel hackers trying to do early boot
> debug, which is a small (but important) cornercase ?

Yes, I think we're on the same page. This patch series is trying to
get the early console working correctly given the current code
assumptions.

-Aaron