linux-kernel - Re: [PATCH v6 5/5] mfd: max77541: Add ADI MAX77541/MAX77540 PMIC Support

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Message-ID: <cdd53e29ca3d8dbfdfa1a2520935e2bf9418313d.camel@gmail.com>
Date:   Tue, 28 Mar 2023 15:26:44 +0200
From:   Nuno Sá <noname.nuno@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Sahin, Okan" <Okan.Sahin@...log.com>
Cc:     Lee Jones <lee@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Cosmin Tanislav <demonsingur@...il.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Caleb Connolly <caleb.connolly@...aro.org>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        "Bolboaca, Ramona" <Ramona.Bolboaca@...log.com>,
        ChiYuan Huang <cy_huang@...htek.com>,
        "Tilki, Ibrahim" <Ibrahim.Tilki@...log.com>,
        William Breathitt Gray <william.gray@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        ChiaEn Wu <chiaen_wu@...htek.com>,
        Haibo Chen <haibo.chen@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v6 5/5]  mfd: max77541: Add ADI MAX77541/MAX77540 PMIC
 Support

On Tue, 2023-03-28 at 15:51 +0300, Andy Shevchenko wrote:
> On Tue, Mar 28, 2023 at 08:26:41AM +0000, Sahin, Okan wrote:
> > > On Wed, 15 Mar 2023, Lee Jones wrote:
> > > > On Tue, 07 Mar 2023, Okan Sahin wrote:
> 
> ...
> 
> > For previous patch(v5), There was feedback from Andy. I did not fix
> > them. 
> 
> Why not? :-)
> 
> > 1) 
> > > They have same regmap except for ADC part of MAX77541.
> > 
> > Extra space in the Subject.
> > 
> > ...
> > 
> > > +#include <linux/of_device.h
> > 
> > This is my fault, I missed this comment. I will fix in following
> > patch(v7).
> > 
> > 2)
> > ...
> > 
> > > +static const struct regmap_config max77541_regmap_config = {
> > > +       .reg_bits   = 8,
> > > +       .val_bits   = 8,
> > 
> > Do you need lock of regmap?
> > 
> > > +};
> > 
> > ...
> > 
> > Since I do not need lock of regmap, I did not change anything in
> > regmap_config (v6). Do I need to answer this question even if I
> > don't need
> > lock of regmap?
> 
> IIRC the lock is opt-out. You need to explicitly disable it if not
> needed.
> 

IIRC, regmap_read() is not really reentrant and it is used in the IIO
driver on the sysfs interface. So, yeah, I think you need the regmap
lock and better just leave the config as is. Yes, the lock is opt-out
so let's not disable it :)

- Nuno Sá