linux-kernel - Re: [LINUX PATCH v2 1/3] clocksource: timer-cadence-ttc: Do not probe TTC device configured as PWM

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Message-ID: <e0f28ec5-b980-490b-a857-5218fe521381@linaro.org>
Date:   Wed, 15 Nov 2023 13:11:28 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     "Sayyed, Mubin" <mubin.sayyed@....com>
Cc:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
        "git (AMD-Xilinx)" <git@....com>,
        "mubin10@...il.com" <mubin10@...il.com>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "Simek, Michal" <michal.simek@....com>
Subject: Re: [LINUX PATCH v2 1/3] clocksource: timer-cadence-ttc: Do not probe
 TTC device configured as PWM

On 15/11/2023 06:55, Sayyed, Mubin wrote:
>>> +	/*
>>> +	 * If pwm-cells property is present in TTC node,
>>> +	 * it would be treated as PWM device.
>>> +	 */
>>> +	if (of_property_read_bool(timer, "#pwm-cells"))
>>> +		return -ENODEV;
>>
>> You will introduce dmesg errors, so regressions.
>>
> [Mubin]: I will change it to "return 0" to avoid dmesg errors.

No, because solution is wrong.

> 
>> This does not look right. What you want is to bind one device driver and
>> choose different functionality based on properties.
> [Mubin]:  I am doing it based on earlier discussion related to AXI Timer PWM driver.  It was suggested to use #pwm-cells property for identifying role of device(PWM/clocksource) https://lore.kernel.org/linux-devicetree/20210513021631.GA878860@robh.at.kernel.org/. 

You are mixing bindings with driver. I said here about driver and yes -
you must use pwm-cells to differentiate that. It's obvious.

So again, one driver binding.

Wrap your emails to mailing list discussion style.

Best regards,
Krzysztof