From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH 1/3] serial: 8250_early: Add earlycon support for AMD Carrizo / Stoneyridge Date: Wed, 14 Mar 2018 18:38:38 +0200 Message-ID: References: <20180314003655.12141-1-djkurtz@chromium.org> <20180314003655.12141-2-djkurtz@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Daniel Kurtz Cc: Ricardo Ribalda Delgado , Aaron Durbin , Greg Kroah-Hartman , Jiri Slaby , Marc Gonzalez , Doug Anderson , Matt Redfearn , Jeffy , "open list:SERIAL DRIVERS" , Linux Kernel Mailing List List-Id: linux-serial@vger.kernel.org On Wed, Mar 14, 2018 at 6:29 PM, Daniel Kurtz wrote: > On Wed, Mar 14, 2018 at 4:54 AM Ricardo Ribalda Delgado < > ricardo.ribalda@gmail.com> wrote: >> On Wed, Mar 14, 2018 at 1:36 AM, Daniel Kurtz > 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