Re: [PATCH 2/5] clocksource/drivers/timer-microchip-pit64b: add Microchip PIT64B support

From: Daniel Lezcano
Date: Mon Jun 24 2019 - 04:07:05 EST

On 21/06/2019 12:34, Claudiu.Beznea@xxxxxxxxxxxxx wrote:
> Hi Daniel,
> On 20.06.2019 11:53, Daniel Lezcano wrote:
>> Hi Claudiu,
>> sorry for the late reply.
> No problem, I understand.
>> On 13/06/2019 16:12, Claudiu.Beznea@xxxxxxxxxxxxx wrote:
>>> Hi Daniel,
>>> On 31.05.2019 13:41, Daniel Lezcano wrote:
>>>> Hi Claudiu,
>>>> On 30/05/2019 09:46, Claudiu.Beznea@xxxxxxxxxxxxx wrote:
>>>>> Hi Daniel,
>>>>> Taking into account the discussion on this tread and the fact that we have
>>>>> no answer from Rob on this topic (I'm talking about [1]), what do you think
>>>>> it would be best for this driver to be accepted the soonest? Would it be OK
>>>>> for you to mimic the approach done by:
>>>>> drivers/clocksource/timer-integrator-ap.c
>>>>> with the following bindings in DT:
>>>>> aliases {
>>>>> arm,timer-primary = &timer2;
>>>>> arm,timer-secondary = &timer1;
>>>>> };
>>>>> also in PIT64B driver?
>>>>> Or do you think re-spinning the Alexandre's patches at [2] (which seems to
>>>>> me like the generic way to do it) would be better?
>>>> This hardware / OS connection problem is getting really annoying for
>>>> everyone and this pattern is repeating itself since several years. It is
>>>> time we fix it properly.
>>>> The first solution looks hackish from my POV. The second approach looks
>>>> nicer and generic as you say. So I would vote for [2]
>>>> flagging approach proposed by Mark [3].
>>> With this flagging approach this would mean a kind unification of
>>> clocksource and clockevent functionalities under a single one, right? So
>>> that the driver would register to the above layers only one device w/ 2
>>> functionalities (clocksource and clockevent)? Please correct me if I'm
>>> wrong? If so, from my point of view this would require major re-working of
>>> clocksource and clockevent subsystems. Correctly if I wrongly understood,
>>> please.
>> Well, actually I was not expecting to change all the framework but just
>> pass a flag to the probe function telling if the node is for a
>> clocksource, a clockevent or both.
> Giving so, whit these proposals I'm thinking at having something like this,
> using Alexandre's new macros from [2] and passing a bitmask to timer's
> probing functions (in the above example adapted only for pit64b driver
> introduced in this thread):

Yes basically that is what I had in mind. Thanks for taking care of
that. However after seeing the code I realize the impact is larger than
expected as all the TIMER_OF_DECLARE will be impacted.

AFAICT, this driver can be converted to the timer-of API. So I think it
makes sense to keep this contained in the API.

In the function timer_of_init(), we can add the parsing of the node and
set the timer-of flags with:


In addition the API:

int timer_of_is_clocksource(struct timer_of *to)
int timer_of_is_clockevents(struct timer_of *to)

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