linux-kernel - Re: [PATCH v2 01/10] regulator: s5m8767: do not use reset value as DVS voltage if GPIO DVS is disabled

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Message-ID: <YVsP96GK9SJFRDkI@robh.at.kernel.org>
Date:   Mon, 4 Oct 2021 09:30:15 -0500
From:   Rob Herring <robh@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>, stable@...r.kernel.org,
        Tomasz Figa <tomasz.figa@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-samsung-soc@...r.kernel.org,
        Michael Turquette <mturquette@...libre.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Lee Jones <lee.jones@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 01/10] regulator: s5m8767: do not use reset value as
 DVS voltage if GPIO DVS is disabled

On Fri, 01 Oct 2021 11:40:57 +0200, Krzysztof Kozlowski wrote:
> The driver and its bindings, before commit 04f9f068a619 ("regulator:
> s5m8767: Modify parsing method of the voltage table of buck2/3/4") were
> requiring to provide at least one safe/default voltage for DVS registers
> if DVS GPIO is not being enabled.
> 
> IOW, if s5m8767,pmic-buck2-uses-gpio-dvs is missing, the
> s5m8767,pmic-buck2-dvs-voltage should still be present and contain one
> voltage.
> 
> This requirement was coming from driver behavior matching this condition
> (none of DVS GPIO is enabled): it was always initializing the DVS
> selector pins to 0 and keeping the DVS enable setting at reset value
> (enabled).  Therefore if none of DVS GPIO is enabled in devicetree,
> driver was configuring the first DVS voltage for buck[234].
> 
> Mentioned commit 04f9f068a619 ("regulator: s5m8767: Modify parsing
> method of the voltage table of buck2/3/4") broke it because DVS voltage
> won't be parsed from devicetree if DVS GPIO is not enabled.  After the
> change, driver will configure bucks to use the register reset value as
> voltage which might have unpleasant effects.
> 
> Fix this by relaxing the bindings constrain: if DVS GPIO is not enabled
> in devicetree (therefore DVS voltage is also not parsed), explicitly
> disable it.
> 
> Cc: <stable@...r.kernel.org>
> Fixes: 04f9f068a619 ("regulator: s5m8767: Modify parsing method of the voltage table of buck2/3/4")
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
> ---
>  .../bindings/regulator/samsung,s5m8767.txt    | 21 +++++++------------
>  drivers/regulator/s5m8767.c                   | 21 ++++++++-----------
>  2 files changed, 17 insertions(+), 25 deletions(-)
> 

Acked-by: Rob Herring <robh@...nel.org>