From: Marc Titinger <mtitinger@baylibre.com> To: Guenter Roeck <linux@roeck-us.net> Cc: jdelvare@suse.com, lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, mturquette@baylibre.com, bcousson@baylibre.com, ptitiano@baylibre.com Subject: Re: [PATCH v2 1/2] hwmon: ina2xx: convert driver to using regmap Date: Wed, 28 Oct 2015 10:23:59 +0100 [thread overview] Message-ID: <5630942F.1020705@baylibre.com> (raw) In-Reply-To: <20151028024711.GA30927@roeck-us.net> On 28/10/2015 03:47, Guenter Roeck wrote: > On Tue, Oct 27, 2015 at 10:51:07AM +0100, Marc Titinger wrote: >> Any sysfs "show" read access from the client app will result in reading >> all registers (8 with ina226). Depending on the host this can limit the >> best achievable read rate. >> >> This changeset allows for individual register accesses through regmap. >> >> Tested with BeagleBone Black (Baylibre-ACME) and ina226. >> >> Signed-off-by: Marc Titinger <mtitinger@baylibre.com> >> --- >> >> v2: >> - rename 'rv' to 'regval' for clarity >> - fix missed smbus_xxx api change to regmap >> - rename ina2xx_do_update to ina2xx_read_reg >> - fix indentation >> >> drivers/hwmon/ina2xx.c | 211 +++++++++++++++++++------------------------------ >> 1 file changed, 82 insertions(+), 129 deletions(-) >> >> diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c >> index 4d28150..5e7ada8 100644 >> --- a/drivers/hwmon/ina2xx.c >> +++ b/drivers/hwmon/ina2xx.c > > [ ... ] >> >> - mutex_lock(&data->update_lock); >> data->rshunt = val; >> status = ina2xx_calibrate(data); >> - mutex_unlock(&data->update_lock); > > I think this can result in a race conditon if multiple processes > try to update the shunt resistor value at the same time in a > multi-core system. There is no guarantee that the value programmed > into the chip matches the value that is written into 'rshunt'. > So I think we still need the mutex, unless you have a better > idea how to avoid the race. > Right, I had that same afterthought when removing the mutex at that position. Fix incoming! M. > Thanks, > Guenter >
WARNING: multiple messages have this Message-ID (diff)
From: Marc Titinger <mtitinger@baylibre.com> To: Guenter Roeck <linux@roeck-us.net> Cc: jdelvare@suse.com, lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, mturquette@baylibre.com, bcousson@baylibre.com, ptitiano@baylibre.com Subject: Re: [lm-sensors] [PATCH v2 1/2] hwmon: ina2xx: convert driver to using regmap Date: Wed, 28 Oct 2015 09:23:59 +0000 [thread overview] Message-ID: <5630942F.1020705@baylibre.com> (raw) In-Reply-To: <20151028024711.GA30927@roeck-us.net> On 28/10/2015 03:47, Guenter Roeck wrote: > On Tue, Oct 27, 2015 at 10:51:07AM +0100, Marc Titinger wrote: >> Any sysfs "show" read access from the client app will result in reading >> all registers (8 with ina226). Depending on the host this can limit the >> best achievable read rate. >> >> This changeset allows for individual register accesses through regmap. >> >> Tested with BeagleBone Black (Baylibre-ACME) and ina226. >> >> Signed-off-by: Marc Titinger <mtitinger@baylibre.com> >> --- >> >> v2: >> - rename 'rv' to 'regval' for clarity >> - fix missed smbus_xxx api change to regmap >> - rename ina2xx_do_update to ina2xx_read_reg >> - fix indentation >> >> drivers/hwmon/ina2xx.c | 211 +++++++++++++++++++------------------------------ >> 1 file changed, 82 insertions(+), 129 deletions(-) >> >> diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c >> index 4d28150..5e7ada8 100644 >> --- a/drivers/hwmon/ina2xx.c >> +++ b/drivers/hwmon/ina2xx.c > > [ ... ] >> >> - mutex_lock(&data->update_lock); >> data->rshunt = val; >> status = ina2xx_calibrate(data); >> - mutex_unlock(&data->update_lock); > > I think this can result in a race conditon if multiple processes > try to update the shunt resistor value at the same time in a > multi-core system. There is no guarantee that the value programmed > into the chip matches the value that is written into 'rshunt'. > So I think we still need the mutex, unless you have a better > idea how to avoid the race. > Right, I had that same afterthought when removing the mutex at that position. Fix incoming! M. > Thanks, > Guenter > _______________________________________________ lm-sensors mailing list lm-sensors@lm-sensors.org http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
next prev parent reply other threads:[~2015-10-28 9:24 UTC|newest] Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-10-19 16:21 [RFC] hwmon: ina2xx: allow for actual measurement bandwidth above 160 Hz Marc Titinger 2015-10-19 16:21 ` [lm-sensors] " Marc Titinger 2015-10-20 1:32 ` Guenter Roeck 2015-10-20 1:32 ` [lm-sensors] " Guenter Roeck 2015-10-20 7:58 ` Marc Titinger 2015-10-20 7:58 ` [lm-sensors] " Marc Titinger 2015-10-20 8:20 ` [PATCH v2] " Marc Titinger 2015-10-20 8:20 ` [lm-sensors] " Marc Titinger 2015-10-20 12:54 ` Guenter Roeck 2015-10-20 12:54 ` [lm-sensors] " Guenter Roeck 2015-10-20 13:17 ` Marc Titinger 2015-10-20 13:17 ` [lm-sensors] " Marc Titinger 2015-10-20 13:30 ` Guenter Roeck 2015-10-20 13:30 ` [lm-sensors] " Guenter Roeck 2015-10-20 13:46 ` Marc Titinger 2015-10-20 13:46 ` [lm-sensors] " Marc Titinger 2015-10-20 17:00 ` Guenter Roeck 2015-10-20 17:00 ` [lm-sensors] " Guenter Roeck 2015-10-21 7:46 ` Marc Titinger 2015-10-21 7:46 ` [lm-sensors] " Marc Titinger 2015-10-20 13:52 ` Michael Turquette 2015-10-20 13:52 ` [lm-sensors] " Michael Turquette 2015-10-23 16:13 ` [RFC] hwmon: ina2xx: port to using remap, improve bandwidth Marc Titinger 2015-10-23 16:13 ` [lm-sensors] " Marc Titinger 2015-10-23 16:49 ` kbuild test robot 2015-10-23 16:49 ` [lm-sensors] " kbuild test robot 2015-10-23 16:52 ` Guenter Roeck 2015-10-23 16:52 ` [lm-sensors] " Guenter Roeck 2015-10-23 20:35 ` Marc Titinger 2015-10-23 20:35 ` [lm-sensors] " Marc Titinger 2015-10-24 2:21 ` Guenter Roeck 2015-10-24 2:21 ` [lm-sensors] " Guenter Roeck 2015-10-24 12:45 ` Guenter Roeck 2015-10-24 12:45 ` [lm-sensors] " Guenter Roeck 2015-10-26 16:24 ` [PATCH 0/2] hwmon: ina2xx: convert driver to using regmap Marc Titinger 2015-10-26 16:24 ` [lm-sensors] " Marc Titinger 2015-10-26 16:24 ` [PATCH 1/2] " Marc Titinger 2015-10-26 16:24 ` [lm-sensors] " Marc Titinger 2015-10-27 1:02 ` Guenter Roeck 2015-10-27 1:02 ` [lm-sensors] " Guenter Roeck 2015-10-27 1:12 ` Guenter Roeck 2015-10-27 1:12 ` [lm-sensors] " Guenter Roeck 2015-10-27 9:51 ` [PATCH v2 " Marc Titinger 2015-10-27 9:51 ` [lm-sensors] " Marc Titinger 2015-10-28 2:47 ` Guenter Roeck 2015-10-28 2:47 ` [lm-sensors] " Guenter Roeck 2015-10-28 9:23 ` Marc Titinger [this message] 2015-10-28 9:23 ` Marc Titinger 2015-10-26 16:24 ` [PATCH 2/2] hwmon: ina2xx: give precedence to DT over checking for platform data Marc Titinger 2015-10-26 16:24 ` [lm-sensors] " Marc Titinger 2015-10-27 1:10 ` Guenter Roeck 2015-10-27 1:10 ` [lm-sensors] " Guenter Roeck 2015-10-27 9:51 ` [PATCH v2 " Marc Titinger 2015-10-27 9:51 ` [lm-sensors] " Marc Titinger 2015-10-23 16:55 ` [RFC] hwmon: ina2xx: port to using remap, improve bandwidth kbuild test robot 2015-10-23 16:55 ` [lm-sensors] " kbuild test robot 2015-10-23 20:10 ` kbuild test robot 2015-10-23 20:10 ` [lm-sensors] " kbuild test robot
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