linux-kernel - Re: [PATCH v2] hwmon: corsair-psu: add reporting of rail mode via debugfs

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Message-ID: <bc1d22d1-45b4-7d49-bedd-f0eafdc035cd@roeck-us.net>
Date:   Wed, 10 Aug 2022 10:29:08 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Wilken Gottwalt <wilken.gottwalt@...teo.net>
Cc:     linux-kernel@...r.kernel.org, Jean Delvare <jdelvare@...e.com>,
        Jonathan Corbet <corbet@....net>, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH v2] hwmon: corsair-psu: add reporting of rail mode via
 debugfs

On 8/10/22 09:56, Wilken Gottwalt wrote:
> On Wed, 10 Aug 2022 09:31:21 -0700
> Guenter Roeck <linux@...ck-us.net> wrote:
> 
>> On 8/10/22 06:53, Wilken Gottwalt wrote:
>>> Add reporting if the PSU is running in single or multi rail mode via
>>> ocpmode debugfs entry. Also update the documentation accordingly.
>>>
>>> Signed-off-by: Wilken Gottwalt <wilken.gottwalt@...teo.net>
>>> ---
>>> Changes in v2:
>>>     - fixed spelling issues in commit message
>>
>> You did not address or even provide feedback on my second comment.
> 
> Oh darn ... sorry, I was quite busy and didn't really pay attention. I will
> answer the earlier mail and think about it.
> 
> Though, maybe you can help me with that what keeps me so busy. Would it be okay
> to use a kthread in a hwmon driver to do sampling (500ms - 10s) in conjunction
> with HWMON_C_UPDATE_INTERVAL, or is this a strict no-no? I know it is actually
> used to set a sample/update rate in a sensor (-register), but this USB-HID
> approach is a pure polling thing. It seems to work quite and enables the driver
> to collect data quite early in the boot process.
> 

It really depends. Is it _necessary_ ? The pwm-fan driver uses a timer for
periodic polling, but that is because it has to. We should not do it purely
for convenience, and from the code I don't immediately see why it would
be necessary.

Guenter