Physical LED Design Proposal

Andrew Jeffery andrew at
Mon Jul 18 12:08:49 AEST 2022

On Wed, 8 Jun 2022, at 23:42, Jayashree D wrote:
> On Tue, Jun 7, 2022 at 9:41 PM Ed Tanous <edtanous at> wrote:
>> On Tue, Jun 7, 2022 at 12:07 AM Jayashree D <srid.11486 at> wrote:
>> >
>> > Hi Team,
>> >
>> > Could you please provide your suggestions on the above design for LED.
>> >
>> > Thanks,
>> > Jayashree
>> >
>> >
>> > On Fri, May 27, 2022 at 12:42 PM Jayashree D <srid.11486 at>
>> wrote:
>> >>
>> >> Hi Team,
>> >>
>> >> Problem Description :
>> >>
>> >> In the existing phosphor-led-sysfs design, it exposes one service per
>> LED. Therefore, multiple services will be created for multiple GPIO pins
>> configured for LED. To abstract this method and also to create LEDs under a
>> single service, a new implementation is proposed.
>> You've kind of jumped directly to a solution without spending any
>> details on why this design is necessary.  What are you trying to
>> achieve?  Why does the existing solution not work?  You allude to
>> multiple services being bad, but you don't really state why, or what's
>> preventing that from working.  This is a section labeled problem
>> description, it needs to describe the problem, ideally in much more
>> length than your solution itself.
>>  The Yosemite V2 Platform combines a Power LED and a System Identification
> LED into a single bicolor blue-yellow LED per host.
> A total of 4 × LEDs will be placed along the front edge of the board in a
> grid.
> The grid will be 2×rows of 2 × LEDs to match the layout of the card slots.
> Based on each host status, blue or yellow led needs to be blink, OFF or ON.
> Therefore, bi-color led needs to be paired as a group and exposed in the
> userspace.
> Based on the existing implementation in phopshor-led-sysfs, pairing groups
> will be difficult, since it exposes one service per LED.
> Therefore, refactoring the phosphor-led-sysfs repo to run under a single
> service and pair a group of LED which represents each host.

It's important that you integrate this justification into your proposal.

Regardless, the proposal should also improve performance on systems 
that were tracking a large number of LEDs. Some p10bmc platforms suffer 


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