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

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> 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).

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;
> 

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