On Fri, Mar 24, 2017 at 12:51 AM, Alison Schofield <amsfield22@xxxxxxxxx> wrote: > On Fri, Mar 24, 2017 at 12:05:20AM +0530, simran singhal wrote: >> The IIO subsystem is redefining iio_dev->mlock to be used by >> the IIO core only for protecting device operating mode changes. >> ie. Changes between INDIO_DIRECT_MODE, INDIO_BUFFER_* modes. >> >> In this driver, mlock was being used to protect hardware state >> changes. Replace it with a lock in the devices global data. > > Hi Simran, > > Please post all revision histories below the --- not just the most > recent. > Sorry, will not repeat this. > Does this lock enforce the needed "atomicity" in the write_frequency > function? I read Jonathans comment on a previous revision about > "ensuring the spi bus frequency and sampling frequency of the device > are changed in an atomic fashion" > By introducing another lock I am protecting read_modify_write and in this way also protecting the designated register that we are about to write. > Is it possible for another spi bus transaction (read or write) to > occur between the read and write in write_frequency? > Gargi has also come up with a solution. https://groups.google.com/forum/#!topic/outreachy-kernel/kzE9CrI5Bd8 Should I do like her as her's also seem correct or go ahead with this. > alisons >> >> Signed-off-by: simran singhal <singhalsimran0@xxxxxxxxx> >> --- >> >> v4: >> -Add mutex_init >> >> drivers/staging/iio/meter/ade7753.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c >> index b71fbd3..30aebaf 100644 >> --- a/drivers/staging/iio/meter/ade7753.c >> +++ b/drivers/staging/iio/meter/ade7753.c >> @@ -80,11 +80,13 @@ >> * @us: actual spi_device >> * @tx: transmit buffer >> * @rx: receive buffer >> + * @lock: protect sensor state >> * @buf_lock: mutex to protect tx and rx >> **/ >> struct ade7753_state { >> struct spi_device *us; >> struct mutex buf_lock; >> + struct mutex lock; /* protect sensor state */ >> u8 tx[ADE7753_MAX_TX] ____cacheline_aligned; >> u8 rx[ADE7753_MAX_RX]; >> }; >> @@ -484,7 +486,7 @@ static ssize_t ade7753_write_frequency(struct device *dev, >> if (!val) >> return -EINVAL; >> >> - mutex_lock(&indio_dev->mlock); >> + mutex_lock(&st->lock); >> >> t = 27900 / val; >> if (t > 0) >> @@ -505,7 +507,7 @@ static ssize_t ade7753_write_frequency(struct device *dev, >> ret = ade7753_spi_write_reg_16(dev, ADE7753_MODE, reg); >> >> out: >> - mutex_unlock(&indio_dev->mlock); >> + mutex_unlock(&st->lock); >> >> return ret ? ret : len; >> } >> @@ -581,6 +583,7 @@ static int ade7753_probe(struct spi_device *spi) >> st = iio_priv(indio_dev); >> st->us = spi; >> mutex_init(&st->buf_lock); >> + mutex_init(&st->lock); >> >> indio_dev->name = spi->dev.driver->name; >> indio_dev->dev.parent = &spi->dev; >> -- >> 2.7.4 >> >> -- >> You received this message because you are subscribed to the Google Groups "outreachy-kernel" group. >> To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@xxxxxxxxxxxxxxxx. >> To post to this group, send email to outreachy-kernel@xxxxxxxxxxxxxxxx. >> To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20170323183520.GA9871%40singhal-Inspiron-5558. >> For more options, visit https://groups.google.com/d/optout. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
