linux-kernel - Re: [patch 4/8] rtc: core: Make the sync offset default more realistic

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Message-ID: <87czzhi40y.fsf@nanos.tec.linutronix.de>
Date:   Fri, 11 Dec 2020 01:23:57 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Miroslav Lichvar <mlichvar@...hat.com>,
        John Stultz <john.stultz@...aro.org>,
        Prarit Bhargava <prarit@...hat.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        linux-rtc@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [patch 4/8] rtc: core: Make the sync offset default more realistic

Alexandre,

On Fri, Dec 11 2020 at 00:59, Alexandre Belloni wrote:
> On 06/12/2020 22:46:17+0100, Thomas Gleixner wrote:
>>  	/* Drivers can revise this default after allocating the device. */
>> -	rtc->set_offset_nsec =  NSEC_PER_SEC / 2;
>> +	rtc->set_offset_nsec =  10 * NSEC_PER_MSEC;
>
> I did retest, on a slow 100kHz i2c bus, with a fairly inconvenient RTC,
> The maximum offset to set the RTC was 4845533ns so I'd say 10ms is too
> large. Should we make that 5ms ?

Sure. As I said I pulled the 10 out of thin air.

> Apart from that, on the series, you can add my
> Acked-by: Alexandre Belloni <alexandre.belloni@...tlin.com>

I'll amend the s/10/5/ throughout the series while queueing the whole
pile in the timers/core branch unless you want it to be handled
differently.

Thanks,

        tglx