Messages in this thread | | | Subject | Re: [PATCH v4 3/4] Add PTP_SYS_OFFSET_PRECISE for driver crosstimestamping | Date | Fri, 06 Nov 2015 18:15:21 -0800 | From | "Christopher Hall" <> |
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Richard/Thomas:
On Tue, 13 Oct 2015 06:59:26 -0700, Richard Cochran <richardcochran@gmail.com> wrote: > On Mon, Oct 12, 2015 at 11:45:21AM -0700, Christopher S. Hall wrote: >> >> +struct ptp_sys_offset_precise { >> + unsigned int rsv[4]; /* Reserved for future use. */ >> + struct ptp_clock_time dev; >> + struct ptp_clock_time sys; >> +}; >> + > > Please put the reserved field at the bottom. Also, since we reading > the raw monotonic time under the hood, we might as well return it in > this struct too. It costs us almost nothing, and having that value > can be useful for characterizing the system oscillator.
Below is my proposal to implement your suggested changes adding monotonic raw to the PTP_SYS_OFFSET_PRECISE ioctl:
Move the reserved field to the end and add monotonic raw to ptp_sys_offset_precise:
struct ptp_sys_offset_precise { struct ptp_clock_time dev; struct ptp_clock_time sys_real; struct ptp_clock_time sys_raw; unsigned int rsv[4]; /* Reserved for future use. */ };
In my previous patch, the getsynctime() prototype is:
int (*getsynctime64)(struct ptp_clock_info *ptp, struct timespec64 *dev, struct timespec64 *sys);
To simplify the PTP callback arguments (not add an additional raw argument), it seems better to replace all of the arguments with a single argument:
int (*getsynctime)(struct ptp_clock_info *ptp, struct correlated_ts *cts);
This requires adding a device time field to the correlated timestamp struct:
struct correlated_ts { int (*get_ts)(struct correlated_ts *ts); u64 system_ts; u64 device_ts; ktime_t system_real; ktime_t system_raw; + ktime_t device; void *private; };
The device time field is filled out by the driver "on the way back" (following completion of get_correlated_timestamp()) to the PTP driver.
The call flow:
PTP driver-> get_synctime() (Ethernet driver)-> get_correlated_timestamp() (Timekeeping)->get_ts (Ethernet driver)
The timestamp argument is the same (type struct correlated_ts *) for all of these calls.
Thanks, Chris
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