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 <mtitin...@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. Thanks, Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
