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From: "Marek Behún" <kabel@kernel.org>
To: Michael Walle <michael@walle.cc>
Cc: andrew@lunn.ch, anthony.l.nguyen@intel.com,
	bigeasy@linutronix.de, davem@davemloft.net,
	dvorax.fuxbrumer@linux.intel.com, f.fainelli@gmail.com,
	hkallweit1@gmail.com, jacek.anaszewski@gmail.com,
	kuba@kernel.org, kurt@linutronix.de, linux-leds@vger.kernel.org,
	netdev@vger.kernel.org, pavel@ucw.cz, sasha.neftin@intel.com,
	vinicius.gomes@intel.com, vitaly.lifshits@intel.com
Subject: Re: [PATCH net-next 5/5] igc: Export LEDs
Date: Tue, 27 Jul 2021 17:28:28 +0200	[thread overview]
Message-ID: <20210727172828.1529c764@thinkpad> (raw)
In-Reply-To: <c56fd3dbe1037a5c2697b311f256b3d8@walle.cc>

Hi,

On Tue, 27 Jul 2021 17:03:53 +0200
Michael Walle <michael@walle.cc> wrote:

> I wasn't talking about ethN being same as the network interface name.
> For clarity I'll use ethernetN now. My question was why would you
> use ethmacN or ethphyN instead if just ethernetN for both. What is
> the reason for having two different names? I'm not sure who is using
> that name anyway. If it is for an user, I don't think he is interested
> in knowing wether that LED is controlled by the PHY or by the MAC.

Suppose that the system has 2 ethernet MACs, each with an attached PHY.
Each MAC-PHY pair has one LED, but one MAC-PHY pair has the LED
attached to the MAC, and the second pair has the LED attached to the
PHY:
     +------+        +------+
     | macA |        | macB |
     +-+--+-+        +-+----+
       |  |            |
      /   +------+   +-+----+
   ledA   | phyA |   | phyB |
          +------+   +----+-+
                          |
                           \
                            ledB

Now suppose that during system initialization the system enumerates
MACs and PHYs in different order:
   macA -> 0      phyA -> 1
   macB -> 1      phyB -> 0

If we used the devicename as you are suggesting, then for the two LEDs
the devicename part would be the same:
  ledA -> macA -> ethernet0
  ledB -> phyB -> ethernet0
although they are clearly on different MACs.

We could create a simple atomically increasing index only for MACs, and
for a LED connected to a PHY, instead of using the PHY's index, we
would look at the attached MAC and use the MAC index.
The problem is that PHYs and MACs are not always attached, and are not
necessarily mapped 1-to-1. It is possible to have a board where one PHY
can connect to 2 different MACs and you can switch between them, and
also vice versa.

> > So it can for example happen that within a network namespace you
> > have only one interface, eth0, but in /sys/class/leds you would see
> >   eth0:green:activity
> >   eth1:green:activity
> > So you would know that there are at least 2 network interfaces on the
> > system, and also with renaming it can happen that the first LED is not
> > in fact connected to the eth0 interface in your network namespace.  
> 
> But the first problem persists wether its named ethernetN or ethphyN,
> no?

No. The N in the "ethphyN" for etherent PHYs is supposed to be unrelated
to the N in "ethN" for interface names. So if you have eth0 network
interface with attached phy ethphy0, this is a coincidence. (That is
why Andrew is proposing to start the index for PHYs at a different
number, like 42.)

Marek

  parent reply	other threads:[~2021-07-27 15:29 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-16 21:24 [PATCH net-next 0/5][pull request] 1GbE Intel Wired LAN Driver Updates 2021-07-16 Tony Nguyen
2021-07-16 21:24 ` [PATCH net-next 1/5] igc: Add possibility to add flex filter Tony Nguyen
2021-07-16 21:24 ` [PATCH net-next 2/5] igc: Integrate flex filter into ethtool ops Tony Nguyen
2021-07-16 21:24 ` [PATCH net-next 3/5] igc: Allow for Flex Filters to be installed Tony Nguyen
2021-07-16 21:24 ` [PATCH net-next 4/5] igc: Make flex filter more flexible Tony Nguyen
2021-07-16 21:24 ` [PATCH net-next 5/5] igc: Export LEDs Tony Nguyen
2021-07-16 21:56   ` Andrew Lunn
2021-07-18 22:10     ` Heiner Kallweit
2021-07-18 22:33       ` Andrew Lunn
2021-07-19  6:17         ` Kurt Kanzenbach
2021-07-19  9:46           ` Jakub Kicinski
2021-07-19  6:06     ` Kurt Kanzenbach
2021-07-19 13:15       ` Andrew Lunn
2021-07-20  8:54         ` Kurt Kanzenbach
2021-07-21 19:18         ` Marek Behún
2021-07-18 22:19   ` Heiner Kallweit
2021-07-19  0:40     ` Andrew Lunn
2021-07-20 15:00       ` Heiner Kallweit
2021-07-20 15:42         ` Andrew Lunn
2021-07-20 20:29           ` Heiner Kallweit
2021-07-21 14:35             ` Andrew Lunn
2021-07-21 16:02               ` Heiner Kallweit
2021-07-21 18:23               ` Pavel Machek
2021-07-21 18:25                 ` Pavel Machek
2021-07-21 18:45             ` Marek Behún
2021-07-21 19:50               ` Andrew Lunn
2021-07-21 20:07                 ` Marek Behún
2021-07-21 20:54                   ` Andrew Lunn
2021-07-21 21:31                     ` Marek Behún
2021-07-21 22:45                     ` Pavel Machek
2021-07-22  1:45                       ` Andrew Lunn
2021-07-22  2:19                         ` Marek Behún
2021-07-21 22:34                   ` Pavel Machek
2021-07-22  3:52                   ` Florian Fainelli
2021-07-26 17:42                   ` Jacek Anaszewski
2021-07-26 18:44                     ` Marek Behún
2021-07-26 20:59                     ` Heiner Kallweit
2021-07-27  0:06                       ` Marek Behún
2021-07-27  1:57                         ` Andrew Lunn
2021-07-27  8:15                           ` Michael Walle
2021-07-27 14:56                             ` Marek Behún
2021-07-27 15:03                               ` Michael Walle
2021-07-27 15:24                                 ` Andrew Lunn
2021-07-27 15:28                                 ` Marek Behún [this message]
2021-07-27 15:53                                   ` Michael Walle
2021-07-27 16:23                                     ` Andrew Lunn
2021-07-27 16:32                                     ` Marek Behún
2021-07-27 16:42                                       ` Andrew Lunn
2021-07-27 19:42                                       ` Michael Walle
2021-07-28 20:43                                       ` Heiner Kallweit
2021-07-29  6:39                                         ` Kurt Kanzenbach
2021-07-29  8:59                                         ` Marek Behún
2021-07-29 21:54                                           ` Heiner Kallweit
2021-08-10 17:29                                         ` Pavel Machek
2021-08-10 17:55                                           ` Marek Behún
2021-08-10 19:53                                             ` Pavel Machek
2021-08-10 20:53                                               ` Marek Behún
2021-08-17 19:02                                                 ` Pavel Machek
2021-08-25 15:26                                                   ` Marek Behún
2021-08-26 12:45                                                     ` Pavel Machek
2021-08-10 20:46                                           ` Heiner Kallweit
2021-08-10 21:21                                             ` Andrew Lunn
2021-07-27 13:55                           ` Marek Behún
2021-08-10 17:22                             ` Documentation for naming LEDs was " Pavel Machek
2021-07-19 21:48   ` Jesse Brandeburg
2021-07-20 13:31     ` Kurt Kanzenbach
2021-07-17  0:30 ` [PATCH net-next 0/5][pull request] 1GbE Intel Wired LAN Driver Updates 2021-07-16 patchwork-bot+netdevbpf
2021-07-17 17:36   ` Andrew Lunn

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