Messages in this thread |  | | Date | Mon, 19 Dec 2022 14:08:32 -0800 | Subject | Re: [Patch net-next v4 01/13] net: dsa: microchip: ptp: add the posix clock support | From | Jacob Keller <> |
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On 12/12/2022 2:26 AM, Arun Ramadoss wrote: > +static int ksz_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) > +{ > + struct ksz_ptp_data *ptp_data = ptp_caps_to_data(ptp); > + struct ksz_device *dev = ptp_data_to_ksz_dev(ptp_data); > + int ret; > + > + mutex_lock(&ptp_data->lock); > + > + if (scaled_ppm) { > + s64 ppb, adj; > + u32 data32; > + > + /* see scaled_ppm_to_ppb() in ptp_clock.c for details */ > + ppb = 1 + scaled_ppm; > + ppb *= 125; > + ppb *= KSZ_PTP_INC_NS; > + ppb <<= KSZ_PTP_SUBNS_BITS - 13; > + adj = div_s64(ppb, NSEC_PER_SEC); > + > + data32 = abs(adj); > + data32 &= PTP_SUBNANOSEC_M; > + if (adj >= 0) > + data32 |= PTP_RATE_DIR; > +
Can you use adjust_by_scaled_ppm or diff_by_scalled_ppm? These work by defining the base increment for your device to achieve nominal nanoseconds, and then perform the multiple+divide to calculate the modified adjustment based on scaled_ppm. The diff_by_scaled_ppm looks like what you want as it takes a base, the scaled adjustment factor and then exports the diff as the 3rd argument. It returns true if the difference is negative so ou can use that to determine if you need to add the PTP_RATE_DIR flag.
If for some reason diff_by_scaled_ppm isn't sufficient for your hardware, at least use scaled_ppm_to_ppb to get the ppb value instead of open coding the conversion.
Thanks, Jake
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