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

Christopher Bostic cbostic at linux.vnet.ibm.com
Wed Jun 7 23:55:45 AEST 2017

On 6/6/17 10:22 PM, Jeremy Kerr wrote:
> Hi Chris,
>> Update GPIO remove behavior to match dev-4.7.
>> On gpio remove: Send a break
>> 		clock, translator, mux = 0
>> 		data, enable = 1
> While this change itself seems okay (leaving GPIOs in a defined state),
> I'm concerned about *why* we need this.
> If there is other code that need GPIOs in a certain state, then that
> code should be doing the required init itself.
Hi Jeremy,

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.

Cronus is a user space layer and presently doesn't modify gpio directly 
in this situation.   It could do this work I suppose but all designers 
involved will need to come to an agreement as to which is the proper 


> Could you add a comment on why this is required?
> Cheers,
> Jeremy

More information about the openbmc mailing list