From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Nelson <eric.nelson@boundarydevices.com>
Date: Sun, 04 Mar 2012 12:45:17 -0700
Subject: [U-Boot] CONFIG_REVISION (was i.MX6: mx6qsabrelite: allow use
 with Freescale 2.6.38 kernels)
In-Reply-To: <4F534D67.3010709@denx.de>
References: <1330728909-12203-1-git-send-email-eric.nelson@boundarydevices.com>	<20120302232545.464F212A7F30@gemini.denx.de>	<4F51BBA9.4090608@googlemail.com>	<20120303093826.C3054126F3B0@gemini.denx.de>	<4F52015A.2080003@googlemail.com>	<20120303133050.690AA82301@gemini.denx.de>
	<4F534D67.3010709@denx.de>
Message-ID: <4F53C64D.4040407@boundarydevices.com>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

On 03/04/2012 04:09 AM, Stefano Babic wrote:
> On 03/03/2012 14:30, Wolfgang Denk wrote:
>> Dear Dirk Behme,
>>
>> <snip>
>>
>> There are 3 commits in this series:
>>
>> [PATCH 1/3] i.MX6: mx6qsabrelite: add CONFIG_REVISION_TAG
>> [PATCH 2/3] i.MX6: mx6qsabrelite: add MACH_TYPE_MX6Q_SABRELITE
>> [PATCH 3/3] i.MX6: mx6qsabrelite: add ext2 support
>>
>> I dislike #1 because it uses the completely undocumented
>> CONFIG_REVISION_TAG, and I agree with Marek's and Stefano's comments.
>
> A lot of boards are currently set CONFIG_REVISION_TAG. Sure, it would be
> nice to document it. To be consistent we should drop this CONFIG_ from
> all boards, or add documentation for it.
>
> However, I am asking if this TAG is really needed. I have searched in
> 2.6.38 Kernel provided by Freescale if the TAG is really evaluated to
> set different revisions of the boards, but I have not found anything. Is
> it  really needed ? If not, we should drop it.
>

The linkage is really indirect. The ATAG item is still supported in the
main-line kernel for ARM:
	http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=arch/arm/kernel/setup.c;h=a255c39612ca3cfa10bddb7c7728216efeeb04d5;hb=HEAD#l704

The breakage I noticed was in the VPU driver, which refused to load
with a zero-value in system_rev. The net result was no video playback
in the Freescale Android ICS release.