[U-Boot] [PATCH 1/2] nitrogen6x: Pass the correct CPU revision to the kernel

[Eric Nelson]

On 03/16/2013 07:58 AM, Fabio Estevam wrote:
> Hi Eric,
>
> On Fri, Mar 15, 2013 at 9:20 PM, Eric Nelson
> <eric.nelson at boundarydevices.com> wrote:
>
>> This is the **board** revision, right?
>>
>> At first glance, the kernel seems to be getting the silicon revision
>> from the same place as get_cpu_rev():
>>
>> https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_3.0.35_1.1.1/arch/arm/mach-mx6/cpu.c#L51
>>
>> http://git.denx.de/u-boot.git/?p=u-boot.git;a=blob;f=arch/arm/cpu/armv7/mx6/soc.c;h=a8aad5dd0a6c8548277021ebe8f6e159dbf31b9b;hb=HEAD#l42
>>
>> Is there a reference to the ATAG that I'm not seeing somewhere?
>
> Ok, so 3.0.35 treats cpu_rev correctly and do not assume this info to
> be passed from the bootloader. I was confused with 2.6.35, where I had
> issues with this on mx53.
>
> So, it seems that nitrogen does not need to pass get_board_rev() at all then?
>
At the moment, it doesn't.

I would really like to see us (the i.MX6 community) standardize
the use of some fuses to specifically mean board revision.

We're contemplating some board changes such as switching the
ethernet PHY and having a convention for the use of a few
bits in OTP would allow us to implement get_board_rev() once in
a common place.

Over the lifetime of most boards, it's likely that at least
one board revision will have software implications and having
a common way to express/detect this could prevent some churn
in board-specific files.

Such a convention would need to have broad sign off though.

Let me know your thoughts on the subject.

Regards,


Eric