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iio: allow userspace to flush the hwfifo with non-blocking reads

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This patch changes the semantics of non-blocking reads so that a
hardware fifo flush is triggered if the available data in the device
buffer is less then the requested size.

This allows userspace to accurately generate hardware fifo flushes, by
doing a non-blocking read with a size greater then the sum of the
device buffer and hardware fifo size.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Octavian Purdila 2015-06-05 15:56:47 +03:00 committed by Jonathan Cameron
parent e20008ed93
commit c6f67a1f55
1 changed files with 9 additions and 9 deletions
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18
drivers/iio/industrialio-buffer.c
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@ -71,8 +71,9 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
if (avail >= to_wait) {
/* force a flush for non-blocking reads */
if (!to_wait && !avail && to_flush)
iio_buffer_flush_hwfifo(indio_dev, buf, to_flush);
if (!to_wait && avail < to_flush)
iio_buffer_flush_hwfifo(indio_dev, buf,
to_flush - avail);
return true;
}
@ -100,8 +101,7 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
struct iio_dev *indio_dev = filp->private_data;
struct iio_buffer *rb = indio_dev->buffer;
size_t datum_size;
size_t to_wait = 0;
size_t to_read;
size_t to_wait;
int ret;
if (!indio_dev->info)
@ -119,14 +119,14 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
if (!datum_size)
return 0;
to_read = min_t(size_t, n / datum_size, rb->watermark);
if (!(filp->f_flags & O_NONBLOCK))
to_wait = to_read;
if (filp->f_flags & O_NONBLOCK)
to_wait = 0;
else
to_wait = min_t(size_t, n / datum_size, rb->watermark);
do {
ret = wait_event_interruptible(rb->pollq,
iio_buffer_ready(indio_dev, rb, to_wait, to_read));
iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size));
if (ret)
return ret;