netdev - Re: Yet another ethernet PHY LED control proposal

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Message-ID: <20200914203006.GA20984@duo.ucw.cz>
Date:   Mon, 14 Sep 2020 22:30:06 +0200
From:   Pavel Machek <pavel@....cz>
To:     Marek Behun <marek.behun@....cz>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>,
        netdev@...r.kernel.org, linux-leds@...r.kernel.org,
        Dan Murphy <dmurphy@...com>,
        Ondřej Jirman <megous@...ous.com>,
        linux-kernel@...r.kernel.org,
        Matthias Schiffer <matthias.schiffer@...tq-group.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: Yet another ethernet PHY LED control proposal

Hi!

> I have been thinking about another way to implement ABI for HW control
> of ethernet PHY connected LEDs.
> 
> This proposal is inspired by the fact that for some time there is a
> movement in the kernel to do transparent HW offloading of things (DSA
> is an example of that).

And it is good proposal.

> So currently we have the `netdev` trigger. When this is enabled for a
> LED, new files will appear in that LED's sysfs directory:
>   - `device_name` where user is supposed to write interface name
>   - `link` if set to 1, the LED will be ON if the interface is linked
>   - `rx` if set to 1, the LED will blink on receive event
>   - `tx` if set to 1, the LED will blink on transmit event
>   - `interval` specifies duration of the LED blink
> 
> Now what is interesting is that almost all combinations of link/rx/tx
> settings are offloadable to a Marvell PHY! (Not to all LEDs, though...)
> 
> So what if we abandoned the idea of a `hw` trigger, and instead just
> allowed a LED trigger to be offloadable, if that specific LED supports
> it?
> 
> For the HW mode for different speed we can just expand the `link` sysfs
> file ABI, so that if user writes a specific speed to this file, instead
> of just "1", the LED will be on if the interface is linked on that
> specific speed. Or maybe another sysfs file could be used for "light on
> N mbps" setting...
> 
> Afterwards we can figure out other possible modes.
> 
> What do you think?

If this can be implemented (and it probably can) it is the best
solution :-).

Best regards,
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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