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From: <Claudiu.Beznea@microchip.com>
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Subject: Re: [PATCH 0/7] add support for clocksource/clockevent DT selection
Date: Tue, 15 Oct 2019 09:23:35 +0000	[thread overview]
Message-ID: <7071b6fa-f7ed-c879-4a43-44100dbe6121@microchip.com> (raw)
In-Reply-To: <14df6e5d-19ef-4ebc-fd11-9953bc3fc44e@linaro.org>

Hi Daniel,

On 13.10.2019 21:16, Daniel Lezcano wrote:
> Hi Claudiu,
> 
> sorry for the delay, I was OoO again.

No problem, thank you for your reply.

> 
> On 03/10/2019 12:43, Claudiu.Beznea@microchip.com wrote:
>>
>>
>> On 02.10.2019 16:35, Claudiu Beznea wrote:
>>> Hi Daniel,
>>>
>>> Taking into account that Rob doesn't agree with the solution proposed in
>>> this series do you think there is a chance to merge this driver as is?
>>
>> Sorry, I was talking here about the driver at [1].
>>
>> [1] https://lore.kernel.org/lkml/1552580772-8499-1-git-send-email-claudiu.beznea@microchip.com/
> 
> Damn! 7 months old. I'm truly sorry we do not have progress on this. Let
> fix this once and for all.
> 
> In the driver:
> 
> ret = of_property_read_u32(node, "clock-frequency", &freq);
> 
> It is unclear how is used this property. It should be the frequency
> driving the timer, but can we get from a clk_get_rate() and a fixed divider?
> 

The timer could be driven by 2 clock sources, one is called peripheral
clock and is the clock that is also driving the IP itself, and one is
called generic clock (this could drive only the timer itself) and should be
at least 3 times lower than the peripheral clock.

We could choose the clock driving the timer by setting the PIT64B_MR.SGCLK
bit (0 - means the timer itself is driven by peripheral clock, 1 - means
the timer is driven by the generic clock).

The timer clock source could be divided by MR.PRES + 1.

So, I used the clock-frequency DT binding to let user choose the timer's
frequency. Based on the value provided via this DT binding the best clock
source and prescaler is chosen via mchp_pit64b_pres_prepare() function.

As the datasheet for the product that is using this IP is open now, I'm
inserting here a link to it [1].

Thank you,
Claudiu Beznea

[1]
http://ww1.microchip.com/downloads/en/DeviceDoc/SAM9X60-Data-Sheet-DS60001579A.pdf

> 

  reply	other threads:[~2019-10-15  9:23 UTC|newest]

Thread overview: 18+ 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 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
2019-09-11  7:34   ` Neil Armstrong
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
2019-09-25 17:19 ` [PATCH 0/7] add support for clocksource/clockevent DT selection 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 [this message]
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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