On Wed, Mar 22, 2017 at 1:15 AM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On 20/03/17 07:39, Gargi Sharma 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 already protects operations in ade7754_write_frequency,
>> there isn't a need to acquire the lock inside ade7754_spi_write_reg_8
>> when writing to the register.
>>
>> Signed-off-by: Gargi Sharma <gs051095@xxxxxxxxx>
> Question inline.
>> ---
>> drivers/staging/iio/meter/ade7754.c | 13 +++++++++++--
>> 1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/staging/iio/meter/ade7754.c b/drivers/staging/iio/meter/ade7754.c
>> index 024463a..eb03469 100644
>> --- a/drivers/staging/iio/meter/ade7754.c
>> +++ b/drivers/staging/iio/meter/ade7754.c
>> @@ -29,6 +29,15 @@ static int ade7754_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
>> struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> struct ade7754_state *st = iio_priv(indio_dev);
>>
>> + if (reg_address == ADE7754_WAVMODE) {
>> + st->tx[0] = ADE7754_WRITE_REG(reg_address);
>> + st->tx[1] = val;
>> +
>> + ret = spi_write(st->us, st->tx, 2);
>> +
>> + return ret;
>> + }
> This block doesn't fit with the description. What's going on here?
When the function ade_spi_write_reg_8() is called inside
ade7754_write_frequency(), we are writing to this( ADE7754_WAVMODE)
register. When writing to this register we don’t need to hold the
buf_lock since ade7754_write_frequency() already takes care of that.
This block of code does not use the buf_lock since that is taken care
of by ade7754_write_frequency().
Gargi
>> +
>> mutex_lock(&st->buf_lock);
>> st->tx[0] = ADE7754_WRITE_REG(reg_address);
>> st->tx[1] = val;
>> @@ -430,7 +439,7 @@ static ssize_t ade7754_write_frequency(struct device *dev,
>> if (!val)
>> return -EINVAL;
>>
>> - mutex_lock(&indio_dev->mlock);
>> + mutex_lock(&st->buf_lock);
>>
>> t = 26000 / val;
>> if (t > 0)
>> @@ -451,7 +460,7 @@ static ssize_t ade7754_write_frequency(struct device *dev,
>> ret = ade7754_spi_write_reg_8(dev, ADE7754_WAVMODE, reg);
>>
>> out:
>> - mutex_unlock(&indio_dev->mlock);
>> + mutex_unlock(&st->buf_lock);
>>
>> return ret ? ret : len;
>> }
>>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
