On 30 March 2017 19:44:26 BST, SIMRAN SINGHAL <singhalsimran0@xxxxxxxxx> wrote: >On Fri, Mar 31, 2017 at 12:02 AM, Jonathan Cameron <jic23@xxxxxxxxxx> >wrote: >> On 28/03/17 19:37, Alison Schofield wrote: >>> On Tue, Mar 28, 2017 at 10:55:17PM +0530, SIMRAN SINGHAL wrote: >>>> 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. >>> >>> I see it protecting this path from being re-entered. My uncertainty >>> is about other paths to read/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. >>> >>> My suggestion would be to wait for feedback on Gargi's patch. >>> (See the Outreachy log about creating similar solutions.) >>> >>> We will not be able to close on this set of patches during the >>> Outreachy application window. You can continue to push for closure >>> beyond the March 30th date as your time allows :) >>> >> It is a close choice between the two approaches. In some ways >> yours is easier to follow, but Gargi's is more elegant. >> >> Lets go with that one for consistency across similar drivers, >> but if you had been the original author and done it this way >> I certainly wouldn't bother asking you to change it! > >Yes, jonathan I am the original author. Sorry, I meant of the driver rather than this improvement. Jonathan > >> >> So in conclusion both patches are good. >> >> Jonathan >> >>> Thanks, >>> alisons >>> >>>> >>>>> 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. >> -- Sent from my Android device with K-9 Mail. Please excuse my brevity. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
