Re: [Linuxptp-users] Issue with initial high jitter(Path Delay Variation)

[Sujatha G. <suj...@gm...>]

Hi Richard,

to avoid the confusion, I am putting both the functions below here
completely.

Please have a look.

static int xlnx_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
{
        struct xlnx_ptp_timer *timer = container_of(ptp, struct
xlnx_ptp_timer,
                                              ptp_clock_info);

        int neg_adj = 0;
        u64 freq = 0;
        u32 diff = 0;
        u32 incval = 0;

        /* External clock source Frequency is 200MHz
   */
        /* adjust the RTC Increment Control register by (1/200MHZ = 5ns)
   */
        /* resolution of the increment register is 1/1048576
   */
        /* hence 5 * 1048576 = 0x500000 - value to be written to the
register */
        incval = 0x500000;

        if (ppb < 0) {
          neg_adj = 1;
          ppb = -ppb;
        }

        freq = incval;
        freq *= ppb;
        diff = div_u64(freq, 1000000000ULL);

        incval = neg_adj ? (incval - diff) : (incval + diff);

        /* Write the adjusted value to the RTC Increment Value Control
Register */
        /* Writing the adjustment value to this register intern adjusts the
nanoseconds register value by the hw */
*out_be32((timer->baseaddr + XTIMER1588_RTC_INCREMENT), incval);*

        return 0;
}


static int xlnx_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        unsigned long flags = 0;
        struct xlnx_ptp_timer *timer = container_of(ptp, struct
xlnx_ptp_timer,
                                              ptp_clock_info);
        struct timespec offset, *then = ns_to_timespec(delta);*

        spin_lock_irqsave(&timer->reg_lock, flags);

        /* Read the seconds and nano seconds from the RTC Seconds and RTC
Nano Seconds Registers */
        xlnx_rtc_offset_read(timer, &offset);

        /* set the current offset values */
        *offset = then;*

        /* Write the seconds and nano seconds to the RTC Seconds and RTC
Nano Seconds Registers */
        xlnx_rtc_offset_write(timer, (const struct timespec *)*&offset*);

        spin_unlock_irqrestore(&timer->reg_lock, flags);
        return 0;
}

Best Regards,
Sujatha

On Thu, Feb 18, 2016 at 3:33 PM, Sujatha Guguloth <suj...@gm...>
wrote:

> Hi Richard,
>
> I am writing the incval to the register in adjfreq after the calculation.I
> had written that in the comments and actual code is below.
> out_be32((timer->baseaddr + XTIMER1588_RTC_INCREMENT), incval);
>
>
> In adjtime: delta is passed to  ns_to_timespec
> then = ns_to_timespec(delta)
> offset = then; /* then is copied to offset */
>  xlnx_rtc_offset_write(timer, (const struct timespec *)&offset); /* This
> offset is written to the register */
>
>
> Best Regards,
> Sujatha
>
>
> On Thu, Feb 18, 2016 at 2:59 PM, Richard Cochran <ric...@gm...
> > wrote:
>
>> Wow, your code is totally broken...
>>
>> On Thu, Feb 18, 2016 at 12:04:22PM +0530, Sujatha Guguloth wrote:
>> > static int xlnx_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
>> > {
>> >         struct xlnx_ptp_timer *timer = container_of(ptp, struct
>> > xlnx_ptp_timer,
>> >                                               ptp_clock_info);
>> >
>> >         int neg_adj = 0;
>> >         u64 freq = 0;
>> >         u32 diff = 0;
>> >         u32 incval = 0;
>> >
>> >         /* External clock source Frequency is 200MHz    which is driving
>> > the timer  */
>> >         /* adjust the RTC Increment Control register by (1/200MHZ =
>> 5ns)  */
>> >         /* resolution of the increment register is 1/1048576
>>   */
>> >         /* hence 5 * 1048576 = 0x500000 - value to be written to the
>> > register */
>> >         incval = 0x500000;
>> >
>> >         if (ppb < 0) {
>> >           neg_adj = 1;
>> >           ppb = -ppb;
>> >         }
>> >
>> >         freq = incval;
>> >         freq *= ppb;
>> >         diff = div_u64(freq, 1000000000ULL);
>> >
>> >         incval = neg_adj ? (incval - diff) : (incval + diff);
>> >
>> >         /* Write the adjusted value to the *RTC Increment Value Control
>> > Register* */
>> >         /* Writing the adjustment value to this register intern adjusts
>> the
>> > nanoseconds register value by the hw */
>>
>> You calculate 'incval' and then do nothing with it.
>>
>> >         return 0;
>> > }
>> >
>> >
>> > static int xlnx_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
>> > {
>> >         unsigned long flags = 0;
>> >         struct xlnx_ptp_timer *timer = container_of(ptp, struct
>> > xlnx_ptp_timer,
>> >                                               ptp_clock_info);
>> >         struct timespec offset, then = ns_to_timespec(delta);
>> >
>> >         spin_lock_irqsave(&timer->reg_lock, flags);
>> >
>> >         /* Read the seconds and nano seconds from the RTC Seconds and
>> RTC
>> > Nano Seconds Registers */
>> >         xlnx_rtc_offset_read(timer, &offset);
>> >
>> >         /* set the current offset values */
>> >         offset = then;
>>
>> You are supposed to add the delta.
>>
>> >         /* Write the seconds and nano seconds to the *RTC Seconds* and
>> *RTC
>> > Nano Seconds* Registers */
>> >         xlnx_rtc_offset_write(timer, (const struct timespec *)&offset);
>> >
>> >         spin_unlock_irqrestore(&timer->reg_lock, flags);
>> >         return 0;
>> > }
>>
>> Good luck,
>> Richard
>>
>
>