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SubjectRe: [PATCH v4] staging: Use buf_lock instead of mlock and Refactor code
On Sun, Mar 19, 2017 at 3:45 PM, Jonathan Cameron <jic23@kernel.org> wrote:
> On 18/03/17 18:44, 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 buf_lock in the devices global data.
>>
>> As buf_lock protects both the adis16060_spi_write() and
>> adis16060_spi_read() functions and both are always called in
>> pair. First write, then read. Thus, refactor the code to have
>> one single function adis16060_spi_write_than_read() which is
>> protected by the existing buf_lock.
>>
>> Signed-off-by: simran singhal <singhalsimran0@gmail.com>
> Hi Simran,
>
> A couple of minor comments and opportunity to further improve
> the, now simpler, code flow.
>
> Thanks,
>
> Jonathan
>> ---
>>
>> v4:
>> -Refactored code
>> -change commit subject
>> -change commit message
>>
>> drivers/staging/iio/gyro/adis16060_core.c | 37 ++++++++++++-------------------
>> 1 file changed, 14 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/staging/iio/gyro/adis16060_core.c b/drivers/staging/iio/gyro/adis16060_core.c
>> index c9d46e7..39ddd55 100644
>> --- a/drivers/staging/iio/gyro/adis16060_core.c
>> +++ b/drivers/staging/iio/gyro/adis16060_core.c
>> @@ -40,7 +40,7 @@ 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_than_read(struct iio_dev *indio_dev, u8 val, u16 *val2)
> val and val2 often have specific meanings in IIO. I'd prefer these to be renamed to
> val => conf (as it sets the configuration) and val2 => val.
>> {
>> int ret;
>> struct adis16060_state *st = iio_priv(indio_dev);
>> @@ -48,17 +48,11 @@ static int adis16060_spi_write(struct iio_dev *indio_dev, u8 val)
>> mutex_lock(&st->buf_lock);
>> st->buf[2] = val; /* 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);
>>
>> @@ -67,10 +61,10 @@ static int adis16060_spi_read(struct iio_dev *indio_dev, u16 *val)
>> * starts to place data MSB first on the DOUT line at
>> * the 6th falling edge of SCLK
>> */
>> - if (!ret)
>> - *val = ((st->buf[0] & 0x3) << 12) |
>> - (st->buf[1] << 4) |
>> - ((st->buf[2] >> 4) & 0xF);
>> + if (!ret)
> Please run checkpatch.pl over your patches. Looks like
> you ended up with spaces instead of a tab in the line above.

OOPS! My bad should have run checkpatch.pl
over patch.

Will correct all the checkpatch.pl issues and resend.

>> + *val2 = ((st->buf[0] & 0x3) << 12) |
>> + (st->buf[1] << 4) |
>> + ((st->buf[2] >> 4) & 0xF);
>> mutex_unlock(&st->buf_lock);
>>
>> return ret;
>> @@ -83,20 +77,17 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
>> {
>> u16 tval = 0;
>> int ret;
>> + struct adis16060_state *st = iio_priv(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);
>> + mutex_lock(&st->buf_lock);
>> + ret = adis16060_spi_write_than_read(indio_dev, chan->address, &tval);
>> if (ret < 0)
>> goto out_unlock;
>>
>> - ret = adis16060_spi_read(indio_dev, &tval);
>> - if (ret < 0)
> This ugly goto construction arguably made sense when there were two of them. Now
> you have only one just bring the mutex_unlock inline and return directly.

Will remove this and resend.

>> - goto out_unlock;
>> -
>> - mutex_unlock(&indio_dev->mlock);
>> + mutex_unlock(&st->buf_lock);
>> *val = tval;
>> return IIO_VAL_INT;
>> case IIO_CHAN_INFO_OFFSET:
>> @@ -112,7 +103,7 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
>> return -EINVAL;
>>
>> out_unlock:
>> - mutex_unlock(&indio_dev->mlock);
>> + mutex_unlock(&st->buf_lock);
>> return ret;
>> }
>>
>>
>

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