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

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Message-ID: <BN9PR11MB55458A882EB4A681C4A63B26F1039@BN9PR11MB5545.namprd11.prod.outlook.com>
Date:   Wed, 2 Mar 2022 16:07:23 +0000
From:   "Sanil, Shruthi" <shruthi.sanil@...el.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        "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

> -----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.

> 
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