On Fri, Mar 31, 2017 at 1:18 AM, Jonathan Cameron <jic23@xxxxxxxxxxxxxxxxxxxxx> wrote: > > > 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. > By reading your pervious comment, I got what you mean!! For consistency, I will do it in the same way Gargi did. > 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. 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