[Design] PSU firmware update

[Lei YU]

On Tue, Jun 4, 2019 at 2:43 PM Neeraj Ladkani <neladk at microsoft.com> wrote:
>
> Are you proposing that if PSU FW is attempted and if system is powered on, the FW update will not start?

Yes, do not perform PSU FW update when the system is powered on, otherwise, it
is considered risky.

> We should not tie framework with these requirements.  If this is really required for a particular platform design then vendor specific tool can have right checks before triggering the update.

This is a good point, I would like to know if there are cases that the PSU
could be updated safely while the system is powered up.
If there are really such cases, then it's true the framework should not
require this, and leave it to vendor-specific tools.

> Also how do we tie this with IPMI?  How does the payload reach BMC and How do we know progress of FW update ?

This design does not involve IPMI at all. The payload is uploaded, processed,
and activated by the same interface as BMC code update.
See doc here: https://github.com/openbmc/docs/blob/master/code-update/code-update.md
So you could use REST APIs or Redfish to do the PSU code update.