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authorOctavian Purdila <octavian.purdila@intel.com>2015-06-05 15:56:47 +0300
committerJonathan Cameron <jic23@kernel.org>2015-06-21 16:51:13 +0300
commitc6f67a1f55a7f8a8373068ca07553bd2b2731949 (patch)
tree936323b1e9e9d2ef184f35fc32f5abd459b0572e /drivers/iio/industrialio-buffer.c
parente20008ed931b9bdd90d1a3fd8c9ef9307547f4ed (diff)
downloadlinux-c6f67a1f55a7f8a8373068ca07553bd2b2731949.tar.xz
iio: allow userspace to flush the hwfifo with non-blocking reads
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>
Diffstat (limited to 'drivers/iio/industrialio-buffer.c')
-rw-r--r--drivers/iio/industrialio-buffer.c18
1 files changed, 9 insertions, 9 deletions
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 6eee1b044c60..f72be48e650c 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -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;