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Date: Mon, 18 Jul 2022 11:38:49 +0930
From: "Andrew Jeffery" <andrew@aj.id.au>
To: "sri d" <srid.11486@gmail.com>, "Ed Tanous" <edtanous@google.com>
Subject: Re: Physical LED Design Proposal
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Cc: Matt Spinler <spinler@us.ibm.com>, "Velumani T-ERS,HCLTech" <velumanit@hcl.com>, openbmc@lists.ozlabs.org, Brad Bishop <bradleyb@fuzziesquirrel.com>, jayashree-d@hcl.com
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On Wed, 8 Jun 2022, at 23:42, Jayashree D wrote:
> On Tue, Jun 7, 2022 at 9:41 PM Ed Tanous <edtanous@google.com> wrote:
>
>> On Tue, Jun 7, 2022 at 12:07 AM Jayashree D <srid.11486@gmail.com> wr=
ote:
>> >
>> > Hi Team,
>> >
>> > Could you please provide your suggestions on the above design for L=
ED.
>> >
>> > Thanks,
>> > Jayashree
>> >
>> >
>> > On Fri, May 27, 2022 at 12:42 PM Jayashree D <srid.11486@gmail.com>
>> 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 p=
ins
>> configured for LED. To abstract this method and also to create LEDs u=
nder 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 Identific=
ation
> LED into a single bicolor blue-yellow LED per host.
> A total of 4 =C3=97 LEDs will be placed along the front edge of the bo=
ard in a
> grid.
> The grid will be 2=C3=97rows of 2 =C3=97 LEDs to match the layout of t=
he card slots.
>
> Based on each host status, blue or yellow led needs to be blink, OFF o=
r ON.
> Therefore, bi-color led needs to be paired as a group and exposed in t=
he
> userspace.
>
> Based on the existing implementation in phopshor-led-sysfs, pairing gr=
oups
> will be difficult, since it exposes one service per LED.
>
> Therefore, refactoring the phosphor-led-sysfs repo to run under a sing=
le
> 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=20
that were tracking a large number of LEDs. Some p10bmc platforms suffer=20
here.

Andrew