AST SOC gpio pass-through support

[Rick Altherr]

On Aug 10, 2017 3:12 AM, "Andrew Jeffery" <andrew at aj.id.au> wrote:

On Thu, 2017-08-10 at 17:01 +0800, Yong Li wrote:
> thanks for your quick response Andrew!

No worries!

> i will read these info deeply. just a quick question, is it possible
> to enable/disable the pass through dynamically after kernel boots?  how?

So there is the concept of runtime pinmuxing[1]: It's possible for a
device to have several pinmux states that can be configured/selected
from process context.



On Quanta Q71L, the hardware strap is used to enable pass through so the
power button works even if the BMC fails to boot. The BMC firmware is
expected to disable the pass through once it is ready to take over. I
believe I sent the patch upstream to allow pinmux to modify the strap
register for this case. That is, pass through is disabled when the user
exports a GPIO to userspace.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ozlabs.org/pipermail/openbmc/attachments/20170810/527ef1ff/attachment.html>