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staging:iio:ad7606: Avoid allocating buffer for each data capture 

Currently the ad7606 driver dynamically allocates and frees a transfer
buffer each time a sample capture is performed in buffered mode, which
introduces unnecessary overhead. The driver state struct already contains a
buffer that is used for transfers in one-shot mode. This buffer is large
enough to hold all samples, but not the timestamp that might be present in
buffered mode. Extend the buffer size to be able to contain the timestamp
and update the buffered capture function to use this buffer.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Lars-Peter Clausen 2016-10-19 19:07:01 +02:00 committed by Jonathan Cameron
parent e79e8027c1
commit f915f7aafb
2 changed files with 6 additions and 12 deletions
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4
drivers/staging/iio/adc/ad7606.h
View File

@ -68,9 +68,9 @@ struct ad7606_state {
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
* 8 * 16-bit samples + 64-bit timestamp
*/
unsigned short data[8] ____cacheline_aligned;
unsigned short data[12] ____cacheline_aligned;
};
struct ad7606_bus_ops {

14
drivers/staging/iio/adc/ad7606_ring.c
View File

@ -46,15 +46,10 @@ static void ad7606_poll_bh_to_ring(struct work_struct *work_s)
struct ad7606_state *st = container_of(work_s, struct ad7606_state,
poll_work);
struct iio_dev *indio_dev = iio_priv_to_dev(st);
__u8 *buf;
int ret;
buf = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
if (!buf)
return;
if (gpio_is_valid(st->pdata->gpio_frstdata)) {
ret = st->bops->read_block(st->dev, 1, buf);
ret = st->bops->read_block(st->dev, 1, st->data);
if (ret)
goto done;
if (!gpio_get_value(st->pdata->gpio_frstdata)) {
@ -67,22 +62,21 @@ static void ad7606_poll_bh_to_ring(struct work_struct *work_s)
goto done;
}
ret = st->bops->read_block(st->dev,
st->chip_info->num_channels - 1, buf + 2);
st->chip_info->num_channels - 1, st->data + 1);
if (ret)
goto done;
} else {
ret = st->bops->read_block(st->dev,
st->chip_info->num_channels, buf);
st->chip_info->num_channels, st->data);
if (ret)
goto done;
}
iio_push_to_buffers_with_timestamp(indio_dev, buf,
iio_push_to_buffers_with_timestamp(indio_dev, st->data,
iio_get_time_ns(indio_dev));
done:
gpio_set_value(st->pdata->gpio_convst, 0);
iio_trigger_notify_done(indio_dev->trig);
kfree(buf);
}
int ad7606_register_ring_funcs_and_init(struct iio_dev *indio_dev)