linux-kernel - Re: [PATCH v8 2/2] clocksource: Add Intel Keem Bay timer support

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Message-ID: <3ff11b85-249f-2f47-cbc4-41d2ab6d168f@linaro.org>
Date:   Wed, 2 Mar 2022 17:26:37 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     "Sanil, Shruthi" <shruthi.sanil@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Cc:     "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        "mgross@...ux.intel.com" <mgross@...ux.intel.com>,
        "Thokala, Srikanth" <srikanth.thokala@...el.com>,
        "Raja Subramanian, Lakshmi Bai" 
        <lakshmi.bai.raja.subramanian@...el.com>,
        "Sangannavar, Mallikarjunappa" 
        <mallikarjunappa.sangannavar@...el.com>
Subject: Re: [PATCH v8 2/2] clocksource: Add Intel Keem Bay timer support

On 02/03/2022 17:07, Sanil, Shruthi wrote:
>> -----Original Message----- From: Daniel Lezcano
>> <daniel.lezcano@...aro.org> Sent: Wednesday, March 2, 2022 3:54 PM 
>> To: Sanil, Shruthi <shruthi.sanil@...el.com>; tglx@...utronix.de; 
>> robh+dt@...nel.org; linux-kernel@...r.kernel.org; 
>> devicetree@...r.kernel.org Cc: andriy.shevchenko@...ux.intel.com;
>> mgross@...ux.intel.com; Thokala, Srikanth
>> <srikanth.thokala@...el.com>; Raja Subramanian, Lakshmi Bai 
>> <lakshmi.bai.raja.subramanian@...el.com>; Sangannavar,
>> Mallikarjunappa <mallikarjunappa.sangannavar@...el.com> Subject:
>> Re: [PATCH v8 2/2] clocksource: Add Intel Keem Bay timer support
>> 
>> On 02/03/2022 11:12, Sanil, Shruthi wrote:
>> 
>> [ ... ]
>> 
>>>>> +	if (!(val & TIM_CONFIG_PRESCALER_ENABLE)) { +
>>>>> pr_err("%pOF: Prescaler is not enabled\n", np); +		ret =
>>>>> -ENODEV; +	}
>>>> 
>>>> Why bail out instead of enabling the prescalar ?
>>> 
>>> Because it is a secure register and it would be updated by the
>>> bootloader.
>> Should it be considered as a firmware bug ?
> 
> No. This is a common driver across products in the series and
> enablement of this bit depends on the project requirements. Hence to
> be sure from driver, we added this check to avoid initialization of
> the driver in the case where it cannot be functional.

I'm not sure to get the meaning of 'project requirements' but (for my 
understanding) why not describe the timer in the DT for such projects?


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