Re: [PATCH 2/3] iio: pressure: Support ROHM BU1390

[Matti Vaittinen]

On 9/17/23 12:26, Jonathan Cameron wrote:
> On Thu, 14 Sep 2023 14:47:44 +0300
> Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
>
> > On 9/10/23 16:22, Jonathan Cameron wrote:
> > > On Wed, 6 Sep 2023 15:37:48 +0300
> > > Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
> > >    
> > > > Support for the ROHM BM1390 pressure sensor. The BM1390GLV-Z can measure
> > > > pressures ranging from 300 hPa to 1300 hPa with configurable measurement
> > > > averaging and internal FIFO. The sensor does also provide temperature
> > > > measurements.
> > > >
> > > > Sensor does also contain IIR filter implemented in HW. The data-sheet
> > > > says the IIR filter can be configured to be "weak", "middle" or
> > > > "strong". Some RMS noise figures are provided in data sheet but no
> > > > accurate maths for the filter configurations is provided. Hence, the IIR
> > > > filter configuration is not supported by this driver and the filter is
> > > > configured to the "middle" setting (at least not for now).
> >
> > > > +
> > > > +static irqreturn_t bm1390_irq_thread_handler(int irq, void *private)
> > > > +{
> > > > +	struct iio_dev *idev = private;
> > > > +	struct bm1390_data *data = iio_priv(idev);
> > > > +	int ret = IRQ_NONE;
> > > > +
> > > > +	mutex_lock(&data->mutex);
> > > > +
> > > > +	if (data->trigger_enabled) {
> > > > +		iio_trigger_poll_nested(data->trig);
> > > > +		ret = IRQ_HANDLED;
> > > > +	}
> > > > +
> > > > +	if (data->state == BM1390_STATE_FIFO) {
> > >
> > > Can this and trigger_enabled be true?
> >
> > Thanks for asking this question. Intention was that these are mutually
> > exclusive. However, I think that the check
> > if (iio_device_get_current_mode(idev) == INDIO_BUFFER_TRIGGERED)
> > in bm1390_buffer_postenable(), before calling the bm1390_fifo_enable()
> > is not 100% race free.
> >
> > I, however, like the idea of having this check in the buffer-enable
> > function - I think it makes the design much more obvious. What I will do
> > is adding another check for:
> > 	if (data->trigger_enable) {
> > 		ret = -EBUSY;
> > 		goto unlock_out;
> > 	}
> >
> > inside the bm1390_fifo_enable() to the section which holds the mutex.
>
> You could make the exclusive nature obvious in the thread_handler by using an
> else if () above.

Right. Thanks.

> > Yours,
> > 	-- Matti

--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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