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Groups > linux.kernel > #1563585

Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross timestamps infrastructure

From Paolo Bonzini <pbonzini@redhat.com>
Newsgroups linux.kernel
Subject Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross timestamps infrastructure
Date 2017-01-20 14:40 +0100
Message-ID <t1HA6-7Ps-25@gated-at.bofh.it> (permalink)
References <t1Gul-7bo-3@gated-at.bofh.it> <t1Gul-7bo-1@gated-at.bofh.it> <t1H76-7EL-85@gated-at.bofh.it> <t1HgL-7Iz-25@gated-at.bofh.it>
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On 20/01/2017 14:07, Marcelo Tosatti wrote:
> On Fri, Jan 20, 2017 at 01:55:27PM +0100, Paolo Bonzini wrote:
>>
>>
>> On 20/01/2017 13:20, Marcelo Tosatti wrote:
>>>  kernel/time/timekeeping.c        |   79 +++++++++++++++++++++++++++++++++++++++
>>
>> Why not leave this in drivers/ptp/ptp_chardev.c?
> 
> timekeeper_lock

Why does emulate_ptp_sys_offset need it, if the current PTP_SYS_OFFSET
code doesn't?  Is the latency acceptable (considering this is a raw spin
lock) or is there a seqlock that we can use instead (such as tk_core.seq
like in get_device_system_crosststamp)?

>>> +		if (ptp->info->emulate_ptp_sys_offset_mean) {
>>> +			err = emulate_ptp_sys_offset(ptp->info, sysoff, arg);
>>> +			break;
>>> +		}
>>
>> I think this should be simply "if (!ptp->info->gettime64)" and,
>> likewise, there should be an emulation based getcrosststamp in
>> ptp_clock_gettime.
>>
>> Paolo
> 
> gettime64 is called directly via ptp_clock_gettime.

Yes, but ptp_clock_gettime can be taught to use getcrosststamp instead.

Paolo

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Thread

[patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross timestamps infrastructure Marcelo Tosatti <mtosatti@redhat.com> - 2017-01-20 13:30 +0100
  Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Paolo Bonzini <pbonzini@redhat.com> - 2017-01-20 14:10 +0100
    Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Marcelo Tosatti <mtosatti@redhat.com> - 2017-01-20 14:20 +0100
      Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Paolo Bonzini <pbonzini@redhat.com> - 2017-01-20 14:40 +0100
        Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Radim Krcmar <rkrcmar@redhat.com> - 2017-01-20 15:10 +0100
          Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Paolo Bonzini <pbonzini@redhat.com> - 2017-01-20 15:30 +0100
            Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Miroslav Lichvar <mlichvar@redhat.com> - 2017-01-20 15:40 +0100
            Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Radim Krcmar <rkrcmar@redhat.com> - 2017-01-20 19:40 +0100
        Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Marcelo Tosatti <mtosatti@redhat.com> - 2017-01-20 16:00 +0100
  Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Richard Cochran <richardcochran@gmail.com> - 2017-01-20 21:30 +0100
    Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Marcelo Tosatti <mtosatti@redhat.com> - 2017-01-23 14:50 +0100
      Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Richard Cochran <richardcochran@gmail.com> - 2017-01-23 19:50 +0100
        Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Paolo Bonzini <pbonzini@redhat.com> - 2017-01-23 20:50 +0100
          Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Richard Cochran <richardcochran@gmail.com> - 2017-01-24 06:50 +0100
          Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Marcelo Tosatti <mtosatti@redhat.com> - 2017-01-24 12:30 +0100
            Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Richard Cochran <richardcochran@gmail.com> - 2017-01-24 12:40 +0100
        Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Marcelo Tosatti <mtosatti@redhat.com> - 2017-01-24 00:10 +0100
          Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Richard Cochran <richardcochran@gmail.com> - 2017-01-24 06:40 +0100
            Re: [patch 4/5] PTP: add PTP_SYS_OFFSET emulation via cross  timestamps infrastructure Miroslav Lichvar <mlichvar@redhat.com> - 2017-01-24 09:20 +0100

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