On 01/04/16 17:53, Alison Schofield wrote:
> Two instances are moved to the new claim/release API:
>
> In the first instance, the driver was using mlock followed by
> iio_buffer_enabled(). Replace that code with the new API to guarantee
> the device stays in direct mode. There is no change in driver behavior.
>
> In the second instance, the driver was not using mlock to hold the
> device in direct mode, but should have been. Here we introduce the
> new API to guarantee direct mode. This is a change in driver behavior.
>
> Signed-off-by: Alison Schofield <amsfiel...@gmail.com>
> ---
> drivers/staging/iio/adc/ad7606_core.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/staging/iio/adc/ad7606_core.c
> b/drivers/staging/iio/adc/ad7606_core.c
> index 6dbc811..f914b8d 100644
> --- a/drivers/staging/iio/adc/ad7606_core.c
> +++ b/drivers/staging/iio/adc/ad7606_core.c
> @@ -88,12 +88,12 @@ static int ad7606_read_raw(struct iio_dev *indio_dev,
>
> switch (m) {
> case IIO_CHAN_INFO_RAW:
> - mutex_lock(&indio_dev->mlock);
> - if (iio_buffer_enabled(indio_dev))
> - ret = -EBUSY;
> - else
> - ret = ad7606_scan_direct(indio_dev, chan->address);
> - mutex_unlock(&indio_dev->mlock);
> + ret = iio_device_claim_direct_mode(indio_dev);
> + if (ret)
> + return ret;
> +
> + ret = ad7606_scan_direct(indio_dev, chan->address);
> + iio_device_release_direct_mode(indio_dev);
>
> if (ret < 0)
> return ret;
> @@ -411,8 +411,9 @@ static irqreturn_t ad7606_interrupt(int irq, void *dev_id)
> struct iio_dev *indio_dev = dev_id;
> struct ad7606_state *st = iio_priv(indio_dev);
>
> - if (iio_buffer_enabled(indio_dev)) {
> + if (!iio_device_claim_direct_mode(indio_dev)) {
> schedule_work(&st->poll_work);
> + iio_device_release_direct_mode(indio_dev);
Unfortunately this won't work. That interrupt is still in traditional non
threaded form. This will take a mutex in a top half interrupt handler
where a sleep cannot occur.
I'm just wondering how expensive it would be to fix this by moving that over
to a threaded handler. In the poll_work case (buffer) it would be cleaner to do
so. I'm really confused what the intended interrupt handler
is in here. I 'think' the sequence is:
Trigger fires the convst pin whether in top half or the bottom half of
a threaded interrupt, but not both - I guess this works, if it is rather
'unusual'.
We then get a interrupt to indicate that it has finished conversion and that
filters through to actually fill the buffer via a traditional top half /
bottom half interrupt handler.
So if we were to convert that to a threaded interrupt (with no top half / non
threaded part), we could drop the schedule_work and just call
ad7606_poll_bh_to_ring from the thread handler.
In the direct read case I doubt we care about the delay in dropping to a
thread prior to signalling the data is ready.
Can't think why this driver is still in staging :)
Lars, any interest from Analog in getting this one cleaned up? Also
do you have any test hardware, if we mess around with this interrupt handling?
Jonathan
> } else {
> st->done = true;
> wake_up_interruptible(&st->wq_data_avail);
>
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