[PATCH linux dev-4.10] drivers/fsi: Break and set pin states on GPIO master remove

[Andrew Geissler]

I think we had this same discussion last time Chris put this on the
mailing list for 4.7 :)   I think we can do better here but we also
(as usual) have a big time crunch.  Can we agree to put this in for
now since our main goal is to just get 4.10 merged and of equal (or
better) function to 4.7?  Chris can create an issue to come up with a
final solution?  Without this change, cronus via the FSP debug does
not work, which is a non-starter for picking this release up by IBM
(and a lot of partners).

I know, in theory, this is easy to fix, but it will require new
testing, potentially new documentation for our users, and is just
adding new function when we're mostly looking to just get a stable
base going.

Andrew

On Thu, Jun 8, 2017 at 5:00 AM, Jeremy Kerr <jk at ozlabs.org> wrote:
> Hi Alistair & Chris,
>
>>> The pins are set here mainly for the benefit of the Cronus debug
>>> tools.   Its common practice in test and bringup labs to switch back and
>>> forth between BMC and FSP-2 with Cronus to access the host processor
>>> CFAMs over FSI.  Without the remove pin state changes Cronus cannot access.
>>
>> As far as I know you have to run "systemctl start fsi-disable.service"
>> to switch over to Cronus mode. I think Jeremy's point is that it
>> should be that service which explicitly sets up the hardware in a
>> suitable mode rather than relying on side-effects from removing the
>> kernel driver.
>
> Yep, spot on.
>
> Also, those side-effects might not be how the GPIOs need to configured
> for the next usage of the FSI bus (which could be Cronus, but could also
> be any other tool). So, let those tools handle the init correctly,
> rather than the kernel making a guess at it.
>
> Cheers,
>
>
> Jeremy