linux-kernel - Re: [RFC PATCH 2/2] mfd: rohm-bd71828: Add power off functionality

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Date: Mon, 25 Mar 2024 14:28:33 +0100
From: Andreas Kemnade <andreas@...nade.info>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: lee@...nel.org, robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
 conor+dt@...nel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [RFC PATCH 2/2] mfd: rohm-bd71828: Add power off functionality

Hi Matti,

On Mon, 25 Mar 2024 14:44:43 +0200
Matti Vaittinen <mazziesaccount@...il.com> wrote:

> Hi Andreas,
> 
> On 3/25/24 14:16, Andreas Kemnade wrote:
> > On Mon, 25 Mar 2024 13:31:15 +0200
> > Matti Vaittinen <mazziesaccount@...il.com> wrote:
> >   
> >> On 3/24/24 22:12, Andreas Kemnade wrote:  
> >>> Since the chip can power off the system, add the corresponding
> >>> functionality.
> >>> Based on https://github.com/kobolabs/Kobo-Reader/raw/master/hw/imx6sll-clara2e/kernel.tar.bz2
> >>> No information source about the magic numbers found.  
> >>
> >> Oh, interesting repository :) Thanks for linking to it! I didn't know
> >> someone had reworked this driver...
> >>  
> > which btw: contains this interesting snippet (output from fdtdump)
> >    bd71828-i2c@4b {
> >                      reg = <0x0000004b>;
> >                      compatible = "rohm,bd71828";
> >                      gpio_int = <0x00000008 0x00000013 0x00000001>;
> >                      gpio_wdogb = <0x00000039 0x00000018 0x00000001>;
> >                      #address-cells = <0x00000001>;
> >                      #size-cells = <0x00000000>;
> >                      pmic@4b {
> >                          compatible = "rohm,bd71828";
> >               	        regulators {
> >                          	BUCK1 {
> >                              		regulator-name = "buck1";
> > 
> > 
> > and to make it work since basically no regulators are registered
> > instead just some regmap_write()s are done to configure something
> > in probe(). It is a pitfall to think that the information below pmic@4b
> > is used, especially since it is not that obvious in the source.  
> 
> Just to ensure there will be no misunderstanding - I have not authored 
> the modifications seen in "Kobo-Reader" repository. Upstream driver does 
> register the regulators - and it does not use the oddly named gpio_int 
> or the gpio_wdogb:

yes, I know it is not from you and I know the general quality in those repos.
But I feel not well pointing to those repositories without issuing the warning
that regulator information in dtb is not an authoritative source for required
regulator settings. Not that someone enables the smoke-generator
functionality...

But lets not go too much offtopic.

Regards,
Andreas