linux-kernel - Re: [PATCH] hwmon: max31790: support to config PWM as TACH

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Message-ID: <29e27f2a-3347-b6f4-2dd9-4c93afea87b7@roeck-us.net>
Date:   Wed, 13 Sep 2023 06:37:21 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Delphine_CC_Chiu/WYHQ/Wiwynn <Delphine_CC_Chiu@...ynn.com>,
        "patrick@...cx.xyz" <patrick@...cx.xyz>,
        Jean Delvare <jdelvare@...e.com>
Cc:     "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] hwmon: max31790: support to config PWM as TACH

On 9/13/23 01:51, Delphine_CC_Chiu/WYHQ/Wiwynn wrote:

[ ... ]

>>
>> This assumes that the channel is configured as pwm.
>> What if the BIOS / ROMMON configured another channel which you want as
>> pwm channel as fan input channel ?
>>
> This will config the channel as TACH.
> Could you provide more information about the scenario you mentioned?
> In our system, there is only BMC that will set the config of fan device.

Please keep in mind that upstream code is not intended to only support
your specific use case, but the use case of others as well. Your system
(the one you have today) may only use the chip for fan speed
measurement. Others may use it use it to control fans, or your hardware
might tomorrow build another system where the chip us used to control
the fans as well. Those use cases should be covered by your patch as well.

Guenter