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Fri, 17 Oct 2025 07:07:00 -0700 (PDT) Message-ID: Subject: Re: [PATCH 22/29] hwmon: (ltc4282) Rely on subsystem locking From: Nuno =?ISO-8859-1?Q?S=E1?= To: Guenter Roeck , Hardware Monitoring Date: Fri, 17 Oct 2025 15:07:33 +0100 In-Reply-To: <20251017130221.1823453-23-linux@roeck-us.net> References: <20251017130221.1823453-1-linux@roeck-us.net> <20251017130221.1823453-23-linux@roeck-us.net> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.1 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2025-10-17 at 06:02 -0700, Guenter Roeck wrote: > Attribute access is now serialized in the hardware monitoring core, > so locking in the driver code is no longer necessary. Drop it. >=20 > Signed-off-by: Guenter Roeck > --- Reviewed-by: Nuno S=C3=A1 > =C2=A0drivers/hwmon/ltc4282.c | 32 ++++---------------------------- > =C2=A01 file changed, 4 insertions(+), 28 deletions(-) >=20 > diff --git a/drivers/hwmon/ltc4282.c b/drivers/hwmon/ltc4282.c > index 44102879694a..b9cad89f2cd9 100644 > --- a/drivers/hwmon/ltc4282.c > +++ b/drivers/hwmon/ltc4282.c > @@ -17,7 +17,6 @@ > =C2=A0#include > =C2=A0#include > =C2=A0#include > -#include > =C2=A0#include > =C2=A0#include > =C2=A0#include > @@ -131,8 +130,6 @@ struct ltc4282_cache { > =C2=A0 > =C2=A0struct ltc4282_state { > =C2=A0 struct regmap *map; > - /* Protect against multiple accesses to the device registers */ > - struct mutex lock; > =C2=A0 struct clk_hw clk_hw; > =C2=A0 /* > =C2=A0 * Used to cache values for VDD/VSOURCE depending which will be us= ed > @@ -281,14 +278,12 @@ static int __ltc4282_read_alarm(struct ltc4282_stat= e > *st, u32 reg, u32 mask, > =C2=A0static int ltc4282_read_alarm(struct ltc4282_state *st, u32 reg, u3= 2 mask, > =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 long *val) > =C2=A0{ > - guard(mutex)(&st->lock); > =C2=A0 return __ltc4282_read_alarm(st, reg, mask, val); > =C2=A0} > =C2=A0 > =C2=A0static int ltc4282_vdd_source_read_in(struct ltc4282_state *st, u32= channel, > =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 long *val) > =C2=A0{ > - guard(mutex)(&st->lock); > =C2=A0 if (!st->in0_1_cache[channel].en) > =C2=A0 return -ENODATA; > =C2=A0 > @@ -300,7 +295,6 @@ static int ltc4282_vdd_source_read_hist(struct > ltc4282_state *st, u32 reg, > =C2=A0{ > =C2=A0 int ret; > =C2=A0 > - guard(mutex)(&st->lock); > =C2=A0 if (!st->in0_1_cache[channel].en) { > =C2=A0 *val =3D *cached; > =C2=A0 return 0; > @@ -317,7 +311,6 @@ static int ltc4282_vdd_source_read_hist(struct > ltc4282_state *st, u32 reg, > =C2=A0static int ltc4282_vdd_source_read_lim(struct ltc4282_state *st, u3= 2 reg, > =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 u32 channel, u32 *cached, = long *val) > =C2=A0{ > - guard(mutex)(&st->lock); > =C2=A0 if (!st->in0_1_cache[channel].en) > =C2=A0 return ltc4282_read_voltage_byte_cached(st, reg, st->vfs_out, > =C2=A0 val, cached); > @@ -328,7 +321,6 @@ static int ltc4282_vdd_source_read_lim(struct > ltc4282_state *st, u32 reg, > =C2=A0static int ltc4282_vdd_source_read_alm(struct ltc4282_state *st, u3= 2 mask, > =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 u32 channel, long *val) > =C2=A0{ > - guard(mutex)(&st->lock); > =C2=A0 if (!st->in0_1_cache[channel].en) { > =C2=A0 /* > =C2=A0 * Do this otherwise alarms can get confused because we clear > @@ -412,9 +404,7 @@ static int ltc4282_read_in(struct ltc4282_state *st, = u32 > attr, long *val, > =C2=A0 =C2=A0=C2=A0 channel, > =C2=A0 =C2=A0=C2=A0 &st- > >in0_1_cache[channel].in_min_raw, val); > =C2=A0 case hwmon_in_enable: > - scoped_guard(mutex, &st->lock) { > - *val =3D st->in0_1_cache[channel].en; > - } > + *val =3D st->in0_1_cache[channel].en; > =C2=A0 return 0; > =C2=A0 case hwmon_in_fault: > =C2=A0 /* > @@ -612,15 +602,11 @@ static int ltc4282_read(struct device *dev, enum > hwmon_sensor_types type, > =C2=A0 case hwmon_power: > =C2=A0 return ltc4282_read_power(st, attr, val); > =C2=A0 case hwmon_energy: > - scoped_guard(mutex, &st->lock) { > - *val =3D st->energy_en; > - } > + *val =3D st->energy_en; > =C2=A0 return 0; > =C2=A0 case hwmon_energy64: > - scoped_guard(mutex, &st->lock) { > - if (st->energy_en) > - return ltc4282_read_energy(st, (s64 *)val); > - } > + if (st->energy_en) > + return ltc4282_read_energy(st, (s64 *)val); > =C2=A0 return -ENODATA; > =C2=A0 default: > =C2=A0 return -EOPNOTSUPP; > @@ -688,7 +674,6 @@ static int __ltc4282_in_write_history(const struct > ltc4282_state *st, u32 reg, > =C2=A0static int ltc4282_in_write_history(struct ltc4282_state *st, u32 r= eg, > =C2=A0 =C2=A0=C2=A0=C2=A0 long lowest, long highest, u32 fs) > =C2=A0{ > - guard(mutex)(&st->lock); > =C2=A0 return __ltc4282_in_write_history(st, reg, lowest, highest, fs); > =C2=A0} > =C2=A0 > @@ -696,8 +681,6 @@ static int ltc4282_power_reset_hist(struct ltc4282_st= ate > *st) > =C2=A0{ > =C2=A0 int ret; > =C2=A0 > - guard(mutex)(&st->lock); > - > =C2=A0 ret =3D ltc4282_write_power_word(st, LTC4282_POWER_LOWEST, > =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 st->power_max); > =C2=A0 if (ret) > @@ -803,7 +786,6 @@ static int ltc4282_vdd_source_write_lim(struct > ltc4282_state *st, u32 reg, > =C2=A0{ > =C2=A0 int ret; > =C2=A0 > - guard(mutex)(&st->lock); > =C2=A0 if (st->in0_1_cache[channel].en) > =C2=A0 ret =3D ltc4282_write_voltage_byte(st, reg, st->vfs_out, val); > =C2=A0 else > @@ -821,7 +803,6 @@ static int ltc4282_vdd_source_reset_hist(struct > ltc4282_state *st, int channel) > =C2=A0 if (channel =3D=3D LTC4282_CHAN_VDD) > =C2=A0 lowest =3D st->vdd; > =C2=A0 > - guard(mutex)(&st->lock); > =C2=A0 if (st->in0_1_cache[channel].en) { > =C2=A0 ret =3D __ltc4282_in_write_history(st, LTC4282_VSOURCE_LOWEST, > =C2=A0 lowest, 0, st->vfs_out); > @@ -861,7 +842,6 @@ static int ltc4282_vdd_source_enable(struct ltc4282_s= tate > *st, int channel, > =C2=A0 int ret, other_chan =3D ~channel & 0x1; > =C2=A0 u8 __val =3D val; > =C2=A0 > - guard(mutex)(&st->lock); > =C2=A0 if (st->in0_1_cache[channel].en =3D=3D !!val) > =C2=A0 return 0; > =C2=A0 > @@ -938,8 +918,6 @@ static int ltc4282_curr_reset_hist(struct ltc4282_sta= te > *st) > =C2=A0{ > =C2=A0 int ret; > =C2=A0 > - guard(mutex)(&st->lock); > - > =C2=A0 ret =3D __ltc4282_in_write_history(st, LTC4282_VSENSE_LOWEST, > =C2=A0 st->vsense_max, 0, 40 * MILLI); > =C2=A0 if (ret) > @@ -974,7 +952,6 @@ static int ltc4282_energy_enable_set(struct ltc4282_s= tate > *st, long val) > =C2=A0{ > =C2=A0 int ret; > =C2=A0 > - guard(mutex)(&st->lock); > =C2=A0 /* setting the bit halts the meter */ > =C2=A0 ret =3D regmap_update_bits(st->map, LTC4282_ADC_CTRL, > =C2=A0 LTC4282_METER_HALT_MASK, > @@ -1699,7 +1676,6 @@ static int ltc4282_probe(struct i2c_client *i2c) > =C2=A0 if (ret) > =C2=A0 return ret; > =C2=A0 > - mutex_init(&st->lock); > =C2=A0 hwmon =3D devm_hwmon_device_register_with_info(dev, "ltc4282", st, > =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0 <c4282_chip_info, > NULL); > =C2=A0 if (IS_ERR(hwmon))