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From:   Thomas Gleixner <tglx@linutronix.de>
To:     lakshmi.sowjanya.d@intel.com, jstultz@google.com,
        giometti@enneenne.com, corbet@lwn.net, linux-kernel@vger.kernel.org
Cc:     x86@kernel.org, linux-doc@vger.kernel.org,
        andriy.shevchenko@linux.intel.com, eddie.dong@intel.com,
        christopher.s.hall@intel.com, pandith.n@intel.com,
        mallikarjunappa.sangannavar@intel.com, thejesh.reddy.t.r@intel.com,
        lakshmi.sowjanya.d@intel.com,
        Peter Hilber <peter.hilber@opensynergy.com>
Subject: Re: [PATCH v1 4/6] pps: generators: Add PPS Generator TIO Driver
In-Reply-To: <87lec15i4b.ffs@tglx>
References: <87lec15i4b.ffs@tglx>
Date:   Wed, 18 Oct 2023 00:58:31 +0200
Message-ID: <87y1g05014.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Tue, Oct 17 2023 at 18:27, Thomas Gleixner wrote:
> static bool pps_arm_next_pulse(struct pps_tio *tio, ktime_t expires)
> {
> 	u64 art;
>
> 	if (!ktime_real_to_base_clock(expires, CSID_X86_ART, &art))
>         	return false;
>
> 	pps_compv_write(tio, art - ART_HW_DELAY_CYCLES);
>         return true;
> }
>
> ktime_real_to_base_clock() does not exist, but that's the function you
> really want to have.

It just occured to me that CLOCK_REALTIME might not really the best
clock to base this on.

It's obvious why this can't be based on CLOCK_MONOTONIC, but I rather
would base this on CLOCK_TAI which at least does not have the issue of
leap seconds and the related nightmares.

Thanks,

        tglx