linux-kernel - Re: [PATCH v4 1/4] clocksource: stm32: convert driver to timer

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Message-ID: <CA+M3ks5CBOXfQCMmUZnkVUNwSGCnzaqdzDZa9ap6NYgDTVspsw@mail.gmail.com>
Date:   Tue, 17 Oct 2017 19:34:21 +0200
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ludovic Barre <ludovic.barre@...com>,
        devicetree@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/4] clocksource: stm32: convert driver to timer_of

2017-10-17 19:09 GMT+02:00 Daniel Lezcano <daniel.lezcano@...aro.org>:
> On 02/10/2017 17:51, Benjamin Gaignard wrote:
>> Convert driver to use timer_of helpers. This allow to remove
>> custom proprietary structure.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...aro.org>
>> ---
>
> [ ... ]
>
>> -     clockevents_config_and_register(&data->evtdev,
>> -                                     DIV_ROUND_CLOSEST(rate, prescaler),
>> -                                     0x1, max_delta);
>> -
>> -     ret = request_irq(irq, stm32_clock_event_handler, IRQF_TIMER,
>> -                     "stm32 clockevent", data);
>> -     if (ret) {
>> -             pr_err("%pOF: failed to request irq.\n", np);
>> -             goto err_get_irq;
>> -     }
>> +     clockevents_config_and_register(&to->clkevt,
>> +                                     timer_of_period(to), 0x60, max_delta);
>
>
> Why 0x1 -> 0x60 ?

Because if the min delta is too small it could generate too much interrupts
and the system will not be able to catch all of them.

>
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