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Date:   Tue, 25 Aug 2020 08:22:18 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "krzk@...nel.org" <krzk@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
CC:     "miquel.raynal@...tlin.com" <miquel.raynal@...tlin.com>,
        "linux-imx@....com" <linux-imx@....com>,
        "vigneshr@...com" <vigneshr@...com>,
        "Anson.Huang@....com" <Anson.Huang@....com>,
        "yibin.gong@....com" <yibin.gong@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "aford173@...il.com" <aford173@...il.com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "richard@....at" <richard@....at>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "daniel.baluta@....com" <daniel.baluta@....com>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "festevam@...il.com" <festevam@...il.com>,
        "han.xu@....com" <han.xu@....com>,
        "jun.li@....com" <jun.li@....com>
Subject: Re: [PATCH 03/16] arm64: dts: imx8mm-beacon-som.dtsi: Align regulator
 names with schema

Hello Krzysztof,

On Tue, 2020-08-25 at 09:50 +0200, krzk@...nel.org wrote:
> On Tue, Aug 25, 2020 at 09:45:00AM +0200, krzk@...nel.org wrote:
> > On Tue, Aug 25, 2020 at 09:25:37AM +0200, krzk@...nel.org wrote:
> > > On Tue, Aug 25, 2020 at 06:51:33AM +0000, Vaittinen, Matti wrote:
> > > > Hello Krzysztof,
> > > > 
> > > > Just some questions - please ignore if I misunderstood the
> > > > impact of
> > > > the change.
> > > > 
> > > > On Mon, 2020-08-24 at 21:06 +0200, Krzysztof Kozlowski wrote:
> > > > > Device tree schema expects regulator names to be
> > > > > lowercase.  This
> > > > > fixes
> > > > > dtbs_check warnings like:
> > > > > 
> > > > >     arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dt.yaml: 
> > > > > pmic@4b:
> > > > > regulators:LDO1:regulator-name:0: 'LDO1' does not match
> > > > > '^ldo[1-6]$'
> > > > > 
> > > > > Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> > > > > ---
> > > > >  .../boot/dts/freescale/imx8mn-ddr4-evk.dts    | 22
> > > > > +++++++++------
> > > > > ----
> > > > >  1 file changed, 11 insertions(+), 11 deletions(-)
> > > > > 
> > > > > diff --git a/arch/arm64/boot/dts/freescale/imx8mn-ddr4-
> > > > > evk.dts
> > > > > b/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts
> > > > > index a1e5483dbbbe..299caed5d46e 100644
> > > > > --- a/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts
> > > > > +++ b/arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dts
> > > > > @@ -60,7 +60,7 @@
> > > > >  
> > > > >  		regulators {
> > > > >  			buck1_reg: BUCK1 {
> > > > > -				regulator-name = "BUCK1";
> > > > > +				regulator-name = "buck1";
> > > > 
> > > > I am not against this change but I would expect seeing some
> > > > other
> > > > patches too? I guess this will change the regulator name in
> > > > regulator
> > > > core, right? So maybe I am mistaken but it looks to me this
> > > > change is
> > > > visible in suppliers, sysfs and debugfs too? Thus changing this
> > > > sounds
> > > > a bit like asking for a nose bleed :) Am I right that the
> > > > impact of
> > > > this change has been thoroughly tested? Are there any other
> > > > patches
> > > > (that I have not seen) related to this change?
> > > 
> > > Oh, crap, the names of regulators in the driver are lowercase,
> > > but they
> > > use of_match_ptr for upper case. Seriously, why making a binding
> > > which
> > > is contradictory to the driver implementation on the first day?
> > > 
> > > The driver goes with binding, right? One expects uppercase, other
> > > lowercase...
> > > 
> > > And tell me, what is now the ABI? The binding or the incorrect
> > > implementation?
> > 
> > Wait, my mistake. I got confused by my own change. The node name
> > stays
> > the same, so of_match will be correct.

Yes. I think so too. Match will still work as earler.

> > 
> > The driver internally already uses lowercase names.

Yep. I was simply thinking that if anyone has been specifying the
regulators as suppliers by name - then this change will change things
(as is seen for LDO5). Additionally, if any user-space SW has been
reading the regulator states from sysfs - then these names will also
change the sysfs. Debugfs change is hopefully not such a big deal.

Whether this really breaks anything is beyond my knowledge as I don't
even have this board. Anyways, I think that by minimum the commit
message should point out that this change will be visible outside DTS
and the BD718x7 driver - up to the user-space.

> > 
> > Everything looks good. I will just double check whether the
> > constraints
> > did not change on the board after boot.
> 
> Constraints look good.
> 
> > > > >  				regulator-min-microvolt =
> > > > > <700000>;
> > > > >  				regulator-max-microvolt =
> > > > > <1300000>;
> > > > >  				regulator-boot-on;
> > > > > @@ -69,7 +69,7 @@
> > > > >  			};
> > > > >  
> > > > >  			buck2_reg: BUCK2 {
> > > > > -				regulator-name = "BUCK2";
> > > > > +				regulator-name = "buck2";
> > > > >  				regulator-min-microvolt =
> > > > > <700000>;
> > > > >  				regulator-max-microvolt =
> > > > > <1300000>;
> > > > >  				regulator-boot-on;
> > > > > @@ -79,14 +79,14 @@
> > > > >  
> > > > >  			buck3_reg: BUCK3 {
> > > > >  				// BUCK5 in datasheet
> > > > > -				regulator-name = "BUCK3";
> > > > > +				regulator-name = "buck3";
> > > > >  				regulator-min-microvolt =
> > > > > <700000>;
> > > > >  				regulator-max-microvolt =
> > > > > <1350000>;
> > > > >  			};
> > > > >  
> > > > >  			buck4_reg: BUCK4 {
> > > > >  				// BUCK6 in datasheet
> > > > > -				regulator-name = "BUCK4";
> > > > > +				regulator-name = "buck4";
> > > > >  				regulator-min-microvolt =
> > > > > <3000000>;
> > > > >  				regulator-max-microvolt =
> > > > > <3300000>;
> > > > >  				regulator-boot-on;
> > > > > @@ -95,7 +95,7 @@
> > > > >  
> > > > >  			buck5_reg: BUCK5 {
> > > > >  				// BUCK7 in datasheet
> > > > > -				regulator-name = "BUCK5";
> > > > > +				regulator-name = "buck5";
> > > > 
> > > > What I see in bd718x7-regulator.c for LDO6 desc is:
> > > > 
> > > >                         /* LDO6 is supplied by buck5 */
> > > >                         .supply_name = "buck5",
> > > > 
> > > > So, is this change going to change the supply-chain for the
> > > > board? Is
> > > > this intended? (Or am I mistaken on what is the impact of
> > > > regulator-
> > > > name property?)
> > 
> > Good point, let me check the supplies.
> 
> This patch actually fixes the supplies which before were not working
> because of case mismatch.
> Before:
> 
>  regulator                      use open bypass  opmode voltage
> current     min     max
> -------------------------------------------------------------------
> --------------------
>  regulator-dummy                  4    5      0
> unknown     0mV     0mA     0mV     0mV
>     LDO6                          1    0      0
> unknown  1200mV     0mA   900mV  1800mV
>  BUCK1                            1    0      0
> unknown   850mV     0mA   700mV  1300mV
>  BUCK2                            2    1      0
> unknown  1000mV     0mA   700mV  1300mV
>     cpu0-
> cpu                      1                                 0mA  1000m
> V  1000mV
>  BUCK3                            1    0      0
> unknown   975mV     0mA   700mV  1350mV
>  BUCK4                            1    0      0
> unknown  3300mV     0mA  3000mV  3300mV
>  BUCK5                            1    0      0
> unknown  1800mV     0mA  1605mV  1995mV
>  BUCK6                            1    0      0
> unknown  1200mV     0mA   800mV  1400mV
>  LDO1                             1    0      0
> unknown  1800mV     0mA  1600mV  1900mV
>  LDO2                             1    0      0
> unknown   800mV     0mA   800mV   900mV
>  LDO3                             1    0      0
> unknown  1800mV     0mA  1800mV  3300mV
>  LDO4                             1    0      0
> unknown   900mV     0mA   900mV  1800mV
>  ldo5                             1    4      0
> unknown  1800mV     0mA  1800mV  1800mV
> 
> 
> 
> After:
>  regulator                      use open bypass  opmode voltage
> current     min     max
> -------------------------------------------------------------------
> --------------------
> buck1                            1    0      0
> unknown   850mV     0mA   700mV  1300mV
>  buck2                            2    1      0
> unknown   850mV     0mA   700mV  1300mV
>     cpu0-
> cpu                      1                                 0mA   850m
> V   850mV
>  buck3                            1    0      0
> unknown   975mV     0mA   700mV  1350mV
>  buck4                            1    0      0
> unknown  3300mV     0mA  3000mV  3300mV
>  buck5                            2    1      0
> unknown  1800mV     0mA  1605mV  1995mV
>     ldo6                          1    0      0 

That was my point :) Before this commit the system has acted
differently - either by accident or by purpose. In any case, the DTS
change will change supply logic and this should probably be mentioned
in commit log to help bisecting possible issues :)

But as I said, I am not opposed to this change - I am merely somewhat
cautious with changes like this.

Best regards
	Matti Vaittinen

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