linux-kernel - Re: [PATCH v2 1/1] hwmon: (pmbus) Add regulator supply into macro

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Message-ID: <c33ec3b6-0e5b-5bb2-1793-c23406c68b40@sylv.io>
Date:   Sat, 5 Nov 2022 02:43:11 +0100
From:   Marcello Sylverster Bauer <sylv@...v.io>
To:     Guenter Roeck <linux@...ck-us.net>,
        Zev Weiss <zev@...ilderbeest.net>
Cc:     Jean Delvare <jdelvare@...e.com>, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>
Subject: Re: [PATCH v2 1/1] hwmon: (pmbus) Add regulator supply into macro


On 11/5/22 00:42, Guenter Roeck wrote:
> On Fri, Nov 04, 2022 at 03:30:30PM -0700, Zev Weiss wrote:
>> On Tue, Feb 22, 2022 at 08:51:04AM PST, Guenter Roeck wrote:
>>> On Mon, Feb 21, 2022 at 12:09:56PM +0100, Marcello Sylvester Bauer wrote:
>>>> Add regulator supply into PWBUS_REGULATOR macro. This makes it optional
>>>> to define a vin-supply in DT. Not defining a supply will add a dummy
>>>> regulator supply instead and only cause the following debug output:
>>>>
>>>> ```
>>>> Looking up vin-supply property in node [...] failed
>>>> ```
>>>>
>>>> Signed-off-by: Marcello Sylvester Bauer <sylv@...v.io>
>>> Applied to hwmon-next. That should give it some time to mature,
>>> and we can pull or modify it if it causes any problems.
>>>
>> Wish I'd caught this sooner, but unfortunately I've just discovered that
>> this does in fact cause breakage on my systems -- having regulator-dummy set
>> as a supply on my PMBus regulators (instead of having them as their own
>> top-level regulators without an upstream supply) leads to enable-count
>> underflow errors when disabling them:
>>
>>      # echo 0 > /sys/bus/platform/devices/efuse01/state
>>      [  906.094477] regulator-dummy: Underflow of regulator enable count
>>      [  906.100563] Failed to disable vout: -EINVAL
>>      [  136.992676] reg-userspace-consumer efuse01: Failed to configure state: -22
>>
>> A simple revert solves the problem for me, but since I'm honestly a little
>> unclear on the intent of the patch itself I'm not sure what a revert might
>> break and hence I don't know if that's necessarily the right fix.  Marcello
>> (or others), any thoughts?
Oh, my bad. I thought this makes it optional to add a supply without 
having a negative effect.
Reverting this patch makes sense, but I'm not sure how else to integrate 
this.

Thanks,
Marcello

> Revert now, ask questions later. I'll send a patch.
>
> Guenter
>
>>
>> Thanks,
>> Zev
>>