Re: [PATCH 1/5] ptp: Added a brand new class driver for ptp clocks.

On Friday 27 August 2010, Richard Cochran wrote:

On Mon, Aug 23, 2010 at 01:21:39PM -0700, john stultz wrote:

quoted

On Thu, 2010-08-19 at 17:38 +0200, Richard Cochran wrote:

quoted

On Thu, Aug 19, 2010 at 02:28:04PM +0200, Arnd Bergmann wrote:

quoted

Have you considered passing a struct timex instead of ppb and ts?

Yes, but the timex is not suitable, IMHO.

Could you expand on this?

We need to able to specify that the call is for a PTP clock. We could
add that to the modes flag, like this:

/*timex.h*/
#define ADJ_PTP_0 0x10000
#define ADJ_PTP_1 0x20000
#define ADJ_PTP_2 0x30000
#define ADJ_PTP_3 0x40000

I can live with this, if everyone else can, too.

My suggestion was actually to have a new syscall with the existing
structure, and pass a clockid_t value to it, similar to your
sys_clock_adjtime(), not change the actual sys_adjtime syscall.
  

quoted

Could we not add a adjustment mode ADJ_SETOFFSET or something that would
provide the instantaneous offset correction?

Yes, but we would also need to add a struct timespec to the struct
timex, in order to get nanosecond resolution. I think it would be
possible to do in the padding at the end?

Yes, that's exactly what the padding is for. Instead of timespec, you can
probably have a extra values for replacing the existing ppm values with
ppb values.

	Arnd