On 11/11/21 16:34, Vladimir Oltean wrote:
That would be me and my ts2phc patches. Sorry for that. Prior to that
change, posix_clock_open() used to simply not populate *phc_index when
passed a path to a PHC. I don't think there's any kernel API to deduce
the PHC number using ioctls on the char device itself, so for my use
case it would be pretty odd to have a PTP device named differently than
/dev/ptpN. Nonetheless, phc2sys does not need to know the exact number
of the PTP clock, and therefore, what I can do is move the error one
level upper, at the caller. I'll try to come up with a patch tomorrow.


Thanks for the quick reply. Understood, digging this out properly (ie. finding the /sys/class/ptp/ptp*/dev file with a matching minor to that of the device node) would add a lot of complexity. However, looking at the alloc_chardev_region() call in the ptp driver (drivers/ptp/ptp_clock.c) reveals the first minor in the requested range is always 0, so it might be ok to assume the PHC index is just the device node minor.

Of course your suggestion of just ignoring the failure in phc2sys would be enough to fix my use case too.

Thanks again for looking at this,
- Ed Branch

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