RE: [PATCH led-next 1/1] leds: mlxreg: Allow multi-instantiation of same name LED for modular systems

[Vadim Pasternak <vadimp@nvidia.com>]

> -----Original Message-----
> From: Pavel Machek <pavel@ucw.cz>
> Sent: Thursday, October 08, 2020 1:05 PM
> To: Vadim Pasternak <vadimp@nvidia.com>
> Cc: Marek Behun <marek.behun@nic.cz>; jacek.anaszewski@gmail.com; linux-
> leds@vger.kernel.org
> Subject: Re: [PATCH led-next 1/1] leds: mlxreg: Allow multi-instantiation of
> same name LED for modular systems
> 
> Hi!
> 
> > > Vadim, the LED core constructs names in form
> > >   device:color:function-enumerator
> > > so if you must have number there, IMO it should be
> > >   mlxreg:green:status-48
> > >   mlxreg:green:status-56
> > >   ...
> >
> > But why you consider it as function enumerator?
> > For example card48, card56 are two different devices of same type.
> > Both have 'status' LED.
> 
> It would help if you could explain what "mlxreg" is.

This is common name for CPLD or FPGA register map, shared between different
platform drivers, while CPLD or FPGA can be connected to CPU trough LPC, SPI or
I2C bus.


> 
> And yes, if you have some kind of device with a status LED, then you can put
> that into the first card. For example sda::status would be accetpable. But
> cardXX is way too generic.
> 
> Perhaps you can explain what "card" is in this context? What is its main
> function?

I provide support for new modular systems which could be equipped with the
different types of replaceable line cards and management board.
The first type of line card is 16x100GbE QSFP28 Ethernet ports.
It equipped with Lattice CPLD device aimed for system and ASIC control, Nvidia FPGA,
Nvidia gearboxes (PHYs).

After that we'll have other line cards: 8x200Gbe QSFP28 Eth ports, 4x400Gbe Eth QSFP-DD,
smart cards equipped with Nvidia ARM CPU for offloading and for fast access to the storage
(EBoF).

For this modular system CPLDs are connected through I2C bus and LED driver will work
over I2C. On main plane CPLD is connected through LPC, and LED driver works over LPC.

Card is common name. But I'd like to avoid some more specific names.

For example, we have huge InfiniBand modular systems with 800 of IB 200G and 400G
ports, which I didn't have yet in upstream. Those system have also replaceable line cards
(so called leaves) and replaceable fabric cards (so called spines).
If I'll give name 'card<bus#>, it will be good also for those systems.
If I'll give more specific name, it'll be not so good name for fabric cards.

I can use name 'fru' instead of 'card' which is standard name and stands for
'Filed Replicable Unit'. Such name will be good for line cards, for fabric cards,
for power units, FANs etcetera.

> 
> Best regards,
> 									Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
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