[PATCH linux] ARM: dts: aspeed: zaius: Enable NC-SI mux

[Rick Altherr]

+maxim

Sounds like U-Boot needs to do some work here.  I'm unclear if the hog
is necessary once U-Boot does the right thing.

On Tue, Mar 7, 2017 at 1:31 PM, Xo Wang <xow at google.com> wrote:
> On Tue, Mar 7, 2017 at 1:21 PM, Rick Altherr <raltherr at google.com> wrote:
>> I don't believe it currently does.  I'm concerned with whether U-Boot
>> or Linux is expected to configure the NC-SI muxes.
>>
>> On Tue, Mar 7, 2017 at 1:19 PM, Xo Wang <xow at google.com> wrote:
>>> On Tue, Mar 7, 2017 at 1:13 PM, Rick Altherr <raltherr at google.com> wrote:
>>>> Why is Linux doing this instead of U-Boot?
>>>>
>>>
>>> Does our U-Boot understand Aspeed GPIO in the device tree? If it does,
>>> then it makes more sense for U-Boot to consume and set these pin
>>> assignments.
>>>
>>> xo
>
> I would think U-Boot is expected to, since that provides the option of
> netbooting from the NC-SI adapter in U-Boot.
>
> In addition, the Linux ftgmac100 driver can't yet handle the NC-SI mux
> changing dynamically (https://github.com/openbmc/openbmc/issues/979).
> So for now the mux must be enabled and selected prior to that driver
> probing. This is the only reason why this assignment exists as a Linux
> gpio-hog: it is set prior to any other driver being probed.
>
> xo