linux-kernel - Re: [PATCH v9] staging: iio: adis16060: Remove iio

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Message-ID: <CALrZqyPD7287QRYMTHnvGjDcqDv1HmvTvixOUum2wxtEdCPd7Q@mail.gmail.com>
Date:   Sat, 25 Mar 2017 23:49:16 +0530
From:   SIMRAN SINGHAL <singhalsimran0@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-iio@...r.kernel.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org,
        outreachy-kernel <outreachy-kernel@...glegroups.com>
Subject: Re: [PATCH v9] staging: iio: adis16060: Remove iio_dev mlock and
 refactor code

On Sat, Mar 25, 2017 at 11:16 PM, Jonathan Cameron <jic23@...nel.org> wrote:
> On 23/03/17 09:20, 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.
>>
>> In the driver, buf_lock protects both the adis16060_spi_write() and
>> adis16060_spi_read() functions and both are always called in pair.
>> First write, then read. Refactor the code to have one single function
>> adis16060_spi_write_then_read() protected by the buf_lock. This removes
>> the need for additional locking via mlock, so this locking is removed.
>>
>> Signed-off-by: simran singhal <singhalsimran0@...il.com>
> Unfortunately I've now pushed out v8 as togreg which is a non rebasing tree.
> As such, could you post a separate patch, on top of that making the
> than -> then change?
>

ok, I will send the patch with than-> then change.

> Thanks,
>
> Jonathan
>> ---
>>
>>  v9:
>>    -Change the name of function from adis16060_spi_write_than_read()
>>     to adis16060_spi_write_then_read(). change "than" to "then" as
>>     its time depended.
>>    -Add mutex_unlock
> As Alison keeps mentioning, ideal is to keep all previous change logs
> here as it allows those who last looked at say v5 to know what changed
> in between without reading a lot of threads!
>>

Sorry, will not repeate this in future.

>>  drivers/staging/iio/gyro/adis16060_core.c | 35 +++++++++----------------------
>>  1 file changed, 10 insertions(+), 25 deletions(-)
>>
>> diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
>> index c9d46e7..9675245 100644
>> --- a/drivers/staging/iio/gyro/adis16060_core.c
>> +++ b/drivers/staging/iio/gyro/adis16060_core.c
>> @@ -40,25 +40,20 @@ struct adis16060_state {
>>
>>  static struct iio_dev *adis16060_iio_dev;
>>
>> -static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val)
>> +static int adis16060_spi_write_then_read(struct iio_dev *indio_dev,
>> +                                      u8 conf, u16 *val)
>>  {
>>       int ret;
>>       struct adis16060_state *st = iio_priv(indio_dev);
>>
>>       mutex_lock(&st->buf_lock);
>> -     st->buf[2] = val; /* The last 8 bits clocked in are latched */
>> +     st->buf[2] = conf; /* The last 8 bits clocked in are latched */
>>       ret = spi_write(st->us_w, st->buf, 3);
>> -     mutex_unlock(&st->buf_lock);
>> -
>> -     return ret;
>> -}
>> -
>> -static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val)
>> -{
>> -     int ret;
>> -     struct adis16060_state *st = iio_priv(indio_dev);
>>
>> -     mutex_lock(&st->buf_lock);
>> +     if (ret < 0) {
>> +             mutex_unlock(&st->buf_lock);
>> +             return ret;
>> +     }
>>
>>       ret = spi_read(st->us_r, st->buf, 3);
>>
>> @@ -86,17 +81,11 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
>>
>>       switch (mask) {
>>       case IIO_CHAN_INFO_RAW:
>> -             /* Take the iio_dev status lock */
>> -             mutex_lock(&indio_dev->mlock);
>> -             ret = adis16060_spi_write(indio_dev, chan->address);
>> +             ret = adis16060_spi_write_then_read(indio_dev,
>> +                                                 chan->address, &tval);
>>               if (ret < 0)
>> -                     goto out_unlock;
>> +                     return ret;
>>
>> -             ret = adis16060_spi_read(indio_dev, &tval);
>> -             if (ret < 0)
>> -                     goto out_unlock;
>> -
>> -             mutex_unlock(&indio_dev->mlock);
>>               *val = tval;
>>               return IIO_VAL_INT;
>>       case IIO_CHAN_INFO_OFFSET:
>> @@ -110,10 +99,6 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
>>       }
>>
>>       return -EINVAL;
>> -
>> -out_unlock:
>> -     mutex_unlock(&indio_dev->mlock);
>> -     return ret;
>>  }
>>
>>  static const struct iio_info adis16060_info = {
>>
>