linux-kernel - Re: [PATCH v2 1/5] hwmon: (max31790) Rework to use regmap

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Message-ID: <CABKa3nquWmP4Hx+eY5CpQ08M2uo2ePpmtZP-6yi45pVOh-Mqzw@mail.gmail.com>
Date:   Fri, 23 Apr 2021 12:55:22 +0200
From:   Václav Kubernát <kubernat@...net.cz>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Jean Delvare <jdelvare@...e.com>, Jonathan Corbet <corbet@....net>,
        linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/5] hwmon: (max31790) Rework to use regmap

Hello.

I agree that it makes sense to swap yes_ranges and no_ranges. I tested
that, but it seems like it doesn't have an effect, I could still see
fan*_input changing (that's where I don't want caching). Does caching
work automatically? As in, all registers are cached by default in
regmap, and only registers that are in the volatile yes_ranges aren't?

Václav

čt 22. 4. 2021 v 3:31 odesílatel Guenter Roeck <linux@...ck-us.net> napsal:
>
> On 4/12/21 7:59 PM, Václav Kubernát wrote:
> > Converting the driver to use regmap makes it more generic. It also makes
> > it a lot easier to debug through debugfs.
> >
> > Signed-off-by: Václav Kubernát <kubernat@...net.cz>
> > ---
> >  drivers/hwmon/Kconfig    |   1 +
> >  drivers/hwmon/max31790.c | 254 ++++++++++++++++++++-------------------
> >  2 files changed, 133 insertions(+), 122 deletions(-)
> >
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> > index 1ecf697d8d99..9f11d036c316 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -1095,6 +1095,7 @@ config SENSORS_MAX6697
> >  config SENSORS_MAX31790
> >       tristate "Maxim MAX31790 sensor chip"
> >       depends on I2C
> > +     select REGMAP_I2C
> >       help
> >         If you say yes here you get support for 6-Channel PWM-Output
> >         Fan RPM Controller.
> > diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
> > index 2c6b333a28e9..e3765ce4444a 100644
> > --- a/drivers/hwmon/max31790.c
> > +++ b/drivers/hwmon/max31790.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/init.h>
> >  #include <linux/jiffies.h>
> >  #include <linux/module.h>
> > +#include <linux/regmap.h>
> >  #include <linux/slab.h>
> >
> >  /* MAX31790 registers */
> > @@ -46,92 +47,53 @@
> >
> >  #define NR_CHANNEL                   6
> >
> > +#define MAX31790_REG_USER_BYTE_67    0x67
> > +
> > +#define BULK_TO_U16(msb, lsb)                (((msb) << 8) + (lsb))
> > +#define U16_MSB(num)                 (((num) & 0xFF00) >> 8)
> > +#define U16_LSB(num)                 ((num) & 0x00FF)
> > +
> > +static const struct regmap_range max31790_ro_range = {
> > +     .range_min = MAX31790_REG_TACH_COUNT(0),
> > +     .range_max = MAX31790_REG_PWMOUT(0) - 1,
> > +};
> > +
> > +static const struct regmap_access_table max31790_wr_table = {
> > +     .no_ranges = &max31790_ro_range,
> > +     .n_no_ranges = 1,
> > +};
> > +
> > +static const struct regmap_range max31790_volatile_ranges[] = {
> > +     regmap_reg_range(MAX31790_REG_TACH_COUNT(0), MAX31790_REG_TACH_COUNT(12)),
> > +     regmap_reg_range(MAX31790_REG_FAN_FAULT_STATUS2, MAX31790_REG_FAN_FAULT_STATUS1),
> > +};
> > +
> > +static const struct regmap_access_table max31790_volatile_table = {
> > +     .no_ranges = max31790_volatile_ranges,
> > +     .n_no_ranges = 2,
> > +     .n_yes_ranges = 0
> > +};
>
> Looks like my reply to this got lost. Other regmap code suggests that
> volatile register ranges are identified with yes_ranges, not with no_ranges.
> "no" seems to mean "not volatile". Please verify and confirm if the
> above code does what you want it to do.
>
> Thanks,
> Guenter