From: <Claudiu.Beznea@microchip.com>
To: <linus.walleij@linaro.org>, <alexandre.belloni@bootlin.com>
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Subject: Re: [PATCH 4/7] dt-bindings: chosen: Add clocksource and clockevent selection
Date: Wed, 11 Sep 2019 07:18:07 +0000 [thread overview]
Message-ID: <a2aca46a-8eb9-d8a8-de42-9850a8a8f44c@microchip.com> (raw)
In-Reply-To: <CACRpkda4mmpbPWa2nD93CvD6HWzcTUDzyyLdQxC2gNB7XiJF3w@mail.gmail.com>
On 11.09.2019 03:03, Linus Walleij wrote:
> External E-Mail
>
>
> On Tue, Sep 10, 2019 at 4:11 PM Alexandre Belloni
> <alexandre.belloni@bootlin.com> wrote:
>> On 10/09/2019 16:08:26+0100, Sudeep Holla wrote:
>>> On Tue, Sep 10, 2019 at 02:51:50PM +0000, Claudiu.Beznea@microchip.com wrote:
>
>>> In that case, why can't we identify capability that with the compatibles
>>> for this timer IP ?
>>>
>>> IOW, I don't like the proposal as it's hardware limitation.
>>
>> To be clear, bot timers are exactly the same but can't be clocksource
>> and clockevent at the same time. Why would we have different compatibles
>> for the exact same IP?
>
> In that case why not just pick the first one you find as clocksource
> and the second one as clock event? As they all come to the
> same timer of init function two simple local state variables can
> solve that:
>
> static bool registered_clocksource;
> static bool registered_clockevent;
>
> probe(timer) {
> if (!registered_clocksource) {
> register_clocksource(timer);
> registrered_clocksource = true;
> return;
> }
> if (!registered_clockevent) {
> register_clockevent(timer);
> registered_clockevent = true;
> return;
> }
> pr_info("surplus timer %p\n", timer);
> }
>
That was also my proposal for the driver I'm sending this series for (see
[1]) but it has been proposed to implement a mechanism similar to this one
in this series (see [2] and [3]).
Thank you,
Claudiu Beznea
[1]
https://lore.kernel.org/lkml/1552580772-8499-1-git-send-email-claudiu.beznea@microchip.com/
[2]
https://lore.kernel.org/lkml/a738fce5-1108-34d7-d255-dfcb86f51c56@linaro.org/
[3]
https://lore.kernel.org/lkml/2f831f1b-c87d-48bd-cf02-2ebb334b964c@linaro.org/
> Clocksource and clockevent are natural singletons so there is
> no need to handle more than one of each in a driver for identical
> hardware.
>
> With the Integrator AP timer there is a real reason to select one over
> the other but as I replied to that patch it is pretty easy to just identify
> which block has this limitation by simply commenting out the IRQ
> line for it from the device tree.
>
> Maybe there is something about this I don't understand.
>
> Yours,
> Linus Walleij
>
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next prev parent reply other threads:[~2019-09-11 7:18 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-10 13:47 [PATCH 0/7] add support for clocksource/clockevent DT selection Claudiu Beznea
2019-09-10 13:47 ` [PATCH 1/7] clocksource/drivers/c-sky: request timer_of_init only for probing CPU Claudiu Beznea
2019-09-10 13:47 ` [PATCH 2/7] clocksource: change timer registration macros Claudiu Beznea
2019-09-10 14:49 ` Marc Zyngier
2019-09-10 14:57 ` Claudiu.Beznea
2019-09-10 13:47 ` [PATCH 3/7] clocksource/timer_of: use BIT() macro Claudiu Beznea
2019-09-10 13:47 ` [PATCH 4/7] dt-bindings: chosen: Add clocksource and clockevent selection Claudiu Beznea
2019-09-10 14:32 ` Sudeep Holla
2019-09-10 14:51 ` Claudiu.Beznea
2019-09-10 15:08 ` Sudeep Holla
2019-09-10 15:10 ` Alexandre Belloni
2019-09-11 0:03 ` Linus Walleij
2019-09-11 7:18 ` Claudiu.Beznea [this message]
2019-09-12 14:18 ` Linus Walleij
2019-09-30 14:32 ` Rob Herring
2019-10-02 13:32 ` Claudiu.Beznea
2019-09-11 7:34 ` Neil Armstrong
2019-09-11 9:14 ` Alexandre Belloni
2019-09-10 13:47 ` [PATCH 5/7] clocksource/drivers/timer-of: add support support for timer's functionalities Claudiu Beznea
2019-09-10 13:47 ` [PATCH 6/7] drivers/clocksource/timer-of: keep declaration on one line Claudiu Beznea
2019-09-10 13:47 ` [PATCH 7/7] clocksource/drivers/integrator-ap: parse the chosen node Claudiu Beznea
2019-09-10 23:48 ` Linus Walleij
2019-09-11 7:14 ` Claudiu.Beznea
2019-09-10 16:05 ` [PATCH 0/7] add support for clocksource/clockevent DT selection John Stultz
2019-09-11 6:52 ` Claudiu.Beznea
2019-09-11 16:06 ` John Stultz
2019-09-25 17:19 ` Daniel Lezcano
2019-09-26 8:42 ` Claudiu.Beznea
2019-10-02 13:35 ` Claudiu.Beznea
2019-10-03 10:43 ` Claudiu.Beznea
2019-10-13 18:16 ` Daniel Lezcano
2019-10-15 9:23 ` Claudiu.Beznea
2019-10-18 20:24 ` Daniel Lezcano
2019-10-21 8:58 ` Claudiu.Beznea
2019-10-21 14:17 ` Daniel Lezcano
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