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:

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.

  # 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.

Thanks,
Richard