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

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Message-ID: <9c017ba9-ac6b-480b-d1f3-120289343101@linaro.org>
Date:   Wed, 26 Jun 2019 12:37:52 +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 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" ?


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