RE: [PATCH net-next 3/3] ptp: derive the device name from the parent device

-----Original Message-----
From: Richard Cochran [mailto:richardcochran@gmail.com]
Sent: Friday, September 21, 2012 10:44 PM
To: Ben Hutchings
Cc: Keller, Jacob E; netdev@vger.kernel.org; David Miller; Kirsher,
Jeffrey T; John Stultz; Vick, Matthew
Subject: Re: [PATCH net-next 3/3] ptp: derive the device name from the
parent device

On Fri, Sep 21, 2012 at 08:01:46PM +0100, Ben Hutchings wrote:

quoted

The ethtool command is useful but setting the parent device may be
even more useful, e.g. you will be able to write udev rules for PHC
devices based on the parent device's identity.

Thinking about this a bit more, it makes no sense to put the parent device
name into clock_name, because that information is redundant.

Agreed.

  # ls -l /sys/class/ptp/ptp0/
  -r--r--r--    1 root root 8192 Jan  1 00:00 clock_name
  -r--r--r--    1 root root 8192 Jan  1 00:00 dev
  lrwxrwxrwx    1 root root    0 Jan  1 00:00 device -> ../../../fec-1:01

I agree that the parent device is useful, and I will add it. However, I
will leave the clock_name as it is, adding a bit more prose to the ABI
description.

The one case where clock_name becomes really important is when you have a
PHY clock, like in the above example, since it provides a way to see that
the clock is *not* related to the MAC.

Agreed. Now that I understand your intent, and with the new parent and ethtool options, I will go ahead and change the ixgbe clock name. This makes more sense to me once I understood the intent.

- Jake

Thanks,
Richard