[Design] PSU firmware update

[Lei YU]

On Tue, Jun 4, 2019 at 1:23 AM Neeraj Ladkani <neladk at microsoft.com> wrote:
>
> 1. Why host power off is a pre-condition? We should add this a PSU pre-requisite to support Live upgrade and activation.

Derek's reply explains the reason why we want to the host power off as
pre-condition.

> 2. How should PSU update impact PSU and battery monitoring ? should there be coordination between sensor monitoring task during update ?

This is a good point. During PSU update, the driver probably should be unbind,
and after the update is one, rebind the driver.
Does that sounds OK?

> 3. PSU may have multiple regions like bootloader, active region and inactive region. We should design to support multiple region update.

I do not have detailed information about this, which is more suitable to let
the vendor-specific tool to handle the multiple regions.
What do you think?

> 4. Can you propose required SEL logs and telemetry requirements as well ?

While I was writing this design doc, I was not thinking about the detailed SEL
logs.
Will need some time to discuss this and see if it shall be covered in this doc
or not.