Re: [PATCH] iio: imu: st_lsm6dsx: track hw FIFO buffering with fifo_mask

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 1 Dec 2019 23:04:26 +0200
Lorenzo Bianconi <lorenzo@kernel.org> wrote:

> > On Thu, 28 Nov 2019 17:42:30 +0200
> > Lorenzo Bianconi <lorenzo@kernel.org> wrote:
> >   
> > > Track hw FIFO state introducing fifo_mask since now the accel sensor
> > > can be enabled during suspend/resume in order to trigger the wake-up
> > > enabling the FIFO in st_lsm6dsx_resume even if it was disabled before
> > > the suspend  
> > 
> > What is the user visible result of not having this patch?
> > 
> > Otherwise looks fine to me.  
> 
> Hi Jonathan,
> 
> I discovered the issue looking at the code. The main point here is after commit
> 4c997dfa692d enable_mask can be modified even by event code and not just by
> FIFO one, so it can't be used to track FIFO status (e.g during suspend-resume).
Ah got it now. I tweaked the explanation a tiny bit and applied to the fixes-togreg
branch of iio.git.

I guess I might be able to apply that other fix now as well. Will check.

Thanks,

Jonathan

> 
> Regards,
> Lorenzo
> 
> > 
> > Jonathan
> >   
> > > 
> > > Fixes: 4c997dfa692d ("iio: imu: st_lsm6dsx: add wakeup-source option")
> > > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > > ---
> > >  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h       |  4 +--
> > >  .../iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c    | 25 +++++++++++--------
> > >  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c  |  4 +--
> > >  3 files changed, 18 insertions(+), 15 deletions(-)
> > > 
> > > diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> > > index c605b153be41..b54aefcdaad4 100644
> > > --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> > > +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h
> > > @@ -351,9 +351,9 @@ struct st_lsm6dsx_sensor {
> > >   * @fifo_lock: Mutex to prevent concurrent access to the hw FIFO.
> > >   * @conf_lock: Mutex to prevent concurrent FIFO configuration update.
> > >   * @page_lock: Mutex to prevent concurrent memory page configuration.
> > > - * @fifo_mode: FIFO operating mode supported by the device.
> > >   * @suspend_mask: Suspended sensor bitmask.
> > >   * @enable_mask: Enabled sensor bitmask.
> > > + * @fifo_mask: Enabled hw FIFO bitmask.
> > >   * @ts_gain: Hw timestamp rate after internal calibration.
> > >   * @ts_sip: Total number of timestamp samples in a given pattern.
> > >   * @sip: Total number of samples (acc/gyro/ts) in a given pattern.
> > > @@ -373,9 +373,9 @@ struct st_lsm6dsx_hw {
> > >  	struct mutex conf_lock;
> > >  	struct mutex page_lock;
> > >  
> > > -	enum st_lsm6dsx_fifo_mode fifo_mode;
> > >  	u8 suspend_mask;
> > >  	u8 enable_mask;
> > > +	u8 fifo_mask;
> > >  	s64 ts_gain;
> > >  	u8 ts_sip;
> > >  	u8 sip;
> > > diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> > > index d416990ae309..bfd4c6306c0b 100644
> > > --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> > > +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> > > @@ -176,17 +176,10 @@ int st_lsm6dsx_set_fifo_mode(struct st_lsm6dsx_hw *hw,
> > >  			     enum st_lsm6dsx_fifo_mode fifo_mode)
> > >  {
> > >  	unsigned int data;
> > > -	int err;
> > >  
> > >  	data = FIELD_PREP(ST_LSM6DSX_FIFO_MODE_MASK, fifo_mode);
> > > -	err = st_lsm6dsx_update_bits_locked(hw, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
> > > -					    ST_LSM6DSX_FIFO_MODE_MASK, data);
> > > -	if (err < 0)
> > > -		return err;
> > > -
> > > -	hw->fifo_mode = fifo_mode;
> > > -
> > > -	return 0;
> > > +	return st_lsm6dsx_update_bits_locked(hw, ST_LSM6DSX_REG_FIFO_MODE_ADDR,
> > > +					     ST_LSM6DSX_FIFO_MODE_MASK, data);
> > >  }
> > >  
> > >  static int st_lsm6dsx_set_fifo_odr(struct st_lsm6dsx_sensor *sensor,
> > > @@ -608,11 +601,17 @@ int st_lsm6dsx_flush_fifo(struct st_lsm6dsx_hw *hw)
> > >  int st_lsm6dsx_update_fifo(struct st_lsm6dsx_sensor *sensor, bool enable)
> > >  {
> > >  	struct st_lsm6dsx_hw *hw = sensor->hw;
> > > +	u8 fifo_mask;
> > >  	int err;
> > >  
> > >  	mutex_lock(&hw->conf_lock);
> > >  
> > > -	if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS) {
> > > +	if (enable)
> > > +		fifo_mask = hw->fifo_mask | BIT(sensor->id);
> > > +	else
> > > +		fifo_mask = hw->fifo_mask & ~BIT(sensor->id);
> > > +
> > > +	if (hw->fifo_mask) {
> > >  		err = st_lsm6dsx_flush_fifo(hw);
> > >  		if (err < 0)
> > >  			goto out;
> > > @@ -642,15 +641,19 @@ int st_lsm6dsx_update_fifo(struct st_lsm6dsx_sensor *sensor, bool enable)
> > >  	if (err < 0)
> > >  		goto out;
> > >  
> > > -	if (hw->enable_mask) {
> > > +	if (fifo_mask) {
> > >  		/* reset hw ts counter */
> > >  		err = st_lsm6dsx_reset_hw_ts(hw);
> > >  		if (err < 0)
> > >  			goto out;
> > >  
> > >  		err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_CONT);
> > > +		if (err < 0)
> > > +			goto out;
> > >  	}
> > >  
> > > +	hw->fifo_mask = fifo_mask;
> > > +
> > >  out:
> > >  	mutex_unlock(&hw->conf_lock);
> > >  
> > > diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> > > index 11b2c7bc8041..6f628c3cd133 100644
> > > --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> > > +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> > > @@ -2300,7 +2300,7 @@ static int __maybe_unused st_lsm6dsx_suspend(struct device *dev)
> > >  		hw->suspend_mask |= BIT(sensor->id);
> > >  	}
> > >  
> > > -	if (hw->fifo_mode != ST_LSM6DSX_FIFO_BYPASS)
> > > +	if (hw->fifo_mask)
> > >  		err = st_lsm6dsx_flush_fifo(hw);
> > >  
> > >  	return err;
> > > @@ -2336,7 +2336,7 @@ static int __maybe_unused st_lsm6dsx_resume(struct device *dev)
> > >  		hw->suspend_mask &= ~BIT(sensor->id);
> > >  	}
> > >  
> > > -	if (hw->enable_mask)
> > > +	if (hw->fifo_mask)
> > >  		err = st_lsm6dsx_set_fifo_mode(hw, ST_LSM6DSX_FIFO_CONT);
> > >  
> > >  	return err;  
> >