linux-kernel - Re: [PATCH RESEND V2 1/3] clocksource/drivers/sysctr: Add optional clock-frequency property

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Message-ID: <8f8aa6e0-5f31-8047-14b5-0e1f65316453@linaro.org>
Date:   Thu, 27 Jun 2019 10:07:08 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Anson Huang <anson.huang@....com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        Abel Vesa <abel.vesa@....com>,
        "ccaione@...libre.com" <ccaione@...libre.com>,
        "angus@...ea.ca" <angus@...ea.ca>,
        "andrew.smirnov@...il.com" <andrew.smirnov@...il.com>,
        "agx@...xcpu.org" <agx@...xcpu.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Cc:     dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH RESEND V2 1/3] clocksource/drivers/sysctr: Add optional
 clock-frequency property

On 27/06/2019 02:43, Anson Huang wrote:
> Hi, Daniel
> 
>> On 26/06/2019 03:42, Anson Huang wrote:
>>> Hi, Daniel
>>>
>>>> On 23/06/2019 14:38, Anson.Huang@....com wrote:
>>>>> From: Anson Huang <Anson.Huang@....com>
>>>>>
>>>>> Systems which use platform driver model for clock driver require the
>>>>> clock frequency to be supplied via device tree when system counter
>>>>> driver is enabled.
>>>>>
>>>>> This is necessary as in the platform driver model the of_clk
>>>>> operations do not work correctly because system counter driver is
>>>>> initialized in early phase of system boot up, and clock driver using
>>>>> platform driver model is NOT ready at that time, it will cause
>>>>> system counter driver initialization failed.
>>>>>
>>>>> Add the optinal clock-frequency to the device tree bindings of the
>>>>> NXP system counter, so the frequency can be handed in and the of_clk
>>>>> operations can be skipped.
>>>>
>>>> Isn't it possible to create a fixed-clock and refer to it? So no need
>>>> to create a specific action before calling timer_of_init() ?
>>>>
>>>
>>> As the clock must be ready before the TIMER_OF_DECLARE, so adding a
>>> CLK_OF_DECLARE_DRIVER in clock driver to ONLY register a fixed-clock?
>>> The system counter's frequency are different on different platforms,
>>> so adding fixed clock in system counter driver is NOT a good idea,
>>> ONLY the DT node or the clock driver can create this fixed clock according to
>> platforms, can you advise where to create this fixed clock is better?
>>
>> Can you point me to a DT with the "nxp,sysctr-timer" ?
> 
> The DT node of system counter is new added in 3/3 of this patch series, also can be found
> from below link:
> https://patchwork.kernel.org/patch/11011703/

Sorry, I was unclear. I meant a patch with the timer defined using a
clock as defined currently in the binding (no clock-frequency).


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