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SubjectRe: [PATCH 2/3] iio: pressure: Support ROHM BU1390
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On 9/17/23 12:26, Jonathan Cameron wrote:
> On Thu, 14 Sep 2023 14:47:44 +0300
> Matti Vaittinen <mazziesaccount@gmail.com> wrote:
>
>> On 9/10/23 16:22, Jonathan Cameron wrote:
>>> On Wed, 6 Sep 2023 15:37:48 +0300
>>> Matti Vaittinen <mazziesaccount@gmail.com> 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

~~ When things go utterly wrong vim users can always type :help! ~~

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