On Tue, 2018-01-23 at 11:40 +0000, Ardelean, Alexandru wrote:
> On Tue, 2018-01-23 at 02:32 +0530, Shreeya Patel wrote:
> >
> > iio_dev->mlock is to be used only by the IIO core for protecting
> > device mode changes between INDIO_DIRECT and INDIO_BUFFER.
> >
> > This patch replaces the use of mlock with the already established
> > buf_lock mutex.
> >
> > Introducing 'unlocked' __ade7758_spi_write_reg_8 and
> > __ade7758_spi_read_reg_8 functions to be used by
> > ade7758_write_samp_freq
> > and ade7758_read_samp_freq which avoids nested locks and maintains
> > atomicity between bus and device frequency changes.
> >
> hey,
>
> note: i took the liberty of re-adjusting the reply list ;
> initial scope seemed too wide ;
> added Barry Song, as he's listed as the author of the driver ;
>
> about the patch:
> overall looks good
> comments inline
>
> >
> > Signed-off-by: Shreeya Patel <shreeya.patel23498@xxxxxxxxx>
> > ---
> > drivers/staging/iio/meter/ade7758.h | 2 +-
> > drivers/staging/iio/meter/ade7758_core.c | 49
> > +++++++++++++++++++++++---------
> > 2 files changed, 37 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/staging/iio/meter/ade7758.h
> > b/drivers/staging/iio/meter/ade7758.h
> > index 6ae78d8..2de81b5 100644
> > --- a/drivers/staging/iio/meter/ade7758.h
> > +++ b/drivers/staging/iio/meter/ade7758.h
> > @@ -111,7 +111,7 @@
> > * @trig: data ready trigger registered with iio
> > * @tx: transmit buffer
> > * @rx: receive buffer
> > - * @buf_lock: mutex to protect tx and rx
> > + * @buf_lock: mutex to protect tx, rx, read and
> > write frequency
> > **/
> > struct ade7758_state {
> > struct spi_device *us;
> > diff --git a/drivers/staging/iio/meter/ade7758_core.c
> > b/drivers/staging/iio/meter/ade7758_core.c
> > index 7b7ffe5..7f8f8c4 100644
> > --- a/drivers/staging/iio/meter/ade7758_core.c
> > +++ b/drivers/staging/iio/meter/ade7758_core.c
> > @@ -24,17 +24,26 @@
> > #include "meter.h"
> > #include "ade7758.h"
> >
> > -int ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8
> > val)
> > +/* Unlocked version of ade7758_spi_write_reg_8 function */
> you can probably remove this comment
Ok. I'll do this change.
>
> >
> > +int __ade7758_spi_write_reg_8(struct device *dev, u8 reg_address,
> > u8 val)
> maybe make this static ;
> this function does not seem to be exported outside of this file
I had thought of doing it so, but then I found that the functions
ade7758_spi_write_reg_8 and ade7758_spi_read_reg_8 were mentioned
under the following comments in the ade7758.h file.
/* At the moment triggers are only used for ring buffer
* filling. This may change!
*/
So I did not make it static.
>
> >
> > {
> > - int ret;
> > struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > struct ade7758_state *st = iio_priv(indio_dev);
> >
> > - mutex_lock(&st->buf_lock);
> > st->tx[0] = ADE7758_WRITE_REG(reg_address);
> > st->tx[1] = val;
> >
> > - ret = spi_write(st->us, st->tx, 2);
> > + return spi_write(st->us, st->tx, 2);
> > +}
> > +
> > +int ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8
> > val)
> > +{
> > + int ret;
> > + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > + struct ade7758_state *st = iio_priv(indio_dev);
> > +
> > + mutex_lock(&st->buf_lock);
> > + ret = __ade7758_spi_write_reg_8(dev, reg_address, val);
> > mutex_unlock(&st->buf_lock);
> >
> > return ret;
> > @@ -91,7 +100,8 @@ static int ade7758_spi_write_reg_24(struct
> > device *dev, u8 reg_address,
> > return ret;
> > }
> >
> > -int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8
> > *val)
> > +/* Unlocked version of ade7758_spi_read_reg_16 function */
> you can probably remove this comment as well
>
> >
> > +int __ade7758_spi_read_reg_8(struct device *dev, u8 reg_address,
> > u8 *val)
> make this static as well
>
> >
> > {
> > struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > struct ade7758_state *st = iio_priv(indio_dev);
> > @@ -111,7 +121,6 @@ int ade7758_spi_read_reg_8(struct device *dev,
> > u8 reg_address, u8 *val)
> > },
> > };
> >
> > - mutex_lock(&st->buf_lock);
> > st->tx[0] = ADE7758_READ_REG(reg_address);
> > st->tx[1] = 0;
> >
> > @@ -124,7 +133,19 @@ int ade7758_spi_read_reg_8(struct device *dev,
> > u8 reg_address, u8 *val)
> > *val = st->rx[0];
> >
> > error_ret:
> > + return ret;
> > +}
> > +
> > +int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8
> > *val)
> > +{
> > + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > + struct ade7758_state *st = iio_priv(indio_dev);
> > + int ret;
> > +
> > + mutex_lock(&st->buf_lock);
> > + ret = __ade7758_spi_read_reg_8(dev, reg_address, val);
> > mutex_unlock(&st->buf_lock);
> > +
> > return ret;
> > }
> >
> > @@ -470,7 +491,7 @@ static int ade7758_read_samp_freq(struct device
> > *dev, int *val)
> > int ret;
> > u8 t;
> >
> > - ret = ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &t);
> > + ret = __ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &t);
> > if (ret)
> > return ret;
> >
> > @@ -503,14 +524,14 @@ static int ade7758_write_samp_freq(struct
> > device *dev, int val)
> > goto out;
> > }
> >
> > - ret = ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, ®);
> > + ret = __ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE,
> > ®);
> > if (ret)
> > goto out;
> >
> > reg &= ~(5 << 3);
> > reg |= t << 5;
> >
> > - ret = ade7758_spi_write_reg_8(dev, ADE7758_WAVMODE, reg);
> > + ret = __ade7758_spi_write_reg_8(dev, ADE7758_WAVMODE,
> > reg);
> >
> > out:
> > return ret;
> > @@ -523,12 +544,13 @@ static int ade7758_read_raw(struct iio_dev
> > *indio_dev,
> > long mask)
> > {
> > int ret;
> > + struct ade7758_state *st = iio_priv(indio_dev);
> >
> > switch (mask) {
> > case IIO_CHAN_INFO_SAMP_FREQ:
> > - mutex_lock(&indio_dev->mlock);
> > + mutex_lock(&st->buf_lock);
> This may be ok.
> I did not seem to find a general consensus on which lock should be
> held here.
> Some drivers use buf_lock, some use the device's mlock.
>
> I guess someone more familiar with the IIO framework would be more
> suited to comment here.
>
> >
> > ret = ade7758_read_samp_freq(&indio_dev->dev,
> > val);
> > - mutex_unlock(&indio_dev->mlock);
> > + mutex_unlock(&st->buf_lock);
> > return ret;
> > default:
> > return -EINVAL;
> > @@ -542,14 +564,15 @@ static int ade7758_write_raw(struct iio_dev
> > *indio_dev,
> > int val, int val2, long mask)
> > {
> > int ret;
> > + struct ade7758_state *st = iio_priv(indio_dev);
> >
> > switch (mask) {
> > case IIO_CHAN_INFO_SAMP_FREQ:
> > if (val2)
> > return -EINVAL;
> > - mutex_lock(&indio_dev->mlock);
> > + mutex_lock(&st->buf_lock);
> same here about the lock
>
> >
> > ret = ade7758_write_samp_freq(&indio_dev->dev,
> > val);
> > - mutex_unlock(&indio_dev->mlock);
> > + mutex_unlock(&st->buf_lock);
> > return ret;
> > default:
> > return -EINVAL;
Thank you for your review :)
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