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

[Guenter Roeck]

On 8/10/22 10:48, Wilken Gottwalt wrote:
> On Wed, 10 Aug 2022 10:29:08 -0700
> Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> > On 8/10/22 09:56, Wilken Gottwalt wrote:
> > > On Wed, 10 Aug 2022 09:31:21 -0700
> > > Guenter Roeck <linux@xxxxxxxxxxxx> 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@xxxxxxxxxx>
> > > > > ---
> > > > > 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.
>
> Together with the polling I would add encountered lowest and highest values and
> the average of basically all available sensors (kind of session statistics). I
> know it is a bit odd, but currently these power supplies are sold again in a
> newer version and people really like to use them in their servers/workstations
> because of the "realtime" data and this driver. No joke, but I really got
> several requests to add this and I must admit I have quite some fun implementing
> it.

That is out of scope for a kernel driver. If desired, a user space application
should do the polling and calculate statistics such as lowest/highest or averages.

Guenter

> Maybe I can provide a patch after I'm done and you can decide if this is okay
> or not. After all I provide an external more enhanced driver via github where
> some features are added, which are a clear no-go. It would be nice to have that
> in mainline, but I'm absolutely fine with a "no".
>
> greetings,
> Wilken