We know that the sample buffer will at most need to hold two 16 bit samples and
the 64 bit aligned 64 bit timestamp. Preallocate a buffer large enough to hold
this instead of allocating and freeing it each time a sample is read.
Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
---
drivers/staging/iio/adc/ad7887.h | 6 ++++--
drivers/staging/iio/adc/ad7887_ring.c | 15 ++-------------
2 files changed, 6 insertions(+), 15 deletions(-)
diff --git a/drivers/staging/iio/adc/ad7887.h b/drivers/staging/iio/adc/ad7887.h
index 2e09e54..71e5092 100644
--- a/drivers/staging/iio/adc/ad7887.h
+++ b/drivers/staging/iio/adc/ad7887.h
@@ -72,9 +72,11 @@ struct ad7887_state {
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
+ * Buffer needs to be large enough to hold two 16 bit samples and a
+ * 64 bit aligned 64 bit timestamp.
*/
-
- unsigned char data[4] ____cacheline_aligned;
+ unsigned char data[ALIGN(4, sizeof(s64)) + sizeof(s64)]
+ ____cacheline_aligned;
};
enum ad7887_supported_device_ids {
diff --git a/drivers/staging/iio/adc/ad7887_ring.c b/drivers/staging/iio/adc/ad7887_ring.c
index b39923b..f11925e 100644
--- a/drivers/staging/iio/adc/ad7887_ring.c
+++ b/drivers/staging/iio/adc/ad7887_ring.c
@@ -73,31 +73,20 @@ static irqreturn_t ad7887_trigger_handler(int irq, void *p)
struct iio_dev *indio_dev = pf->indio_dev;
struct ad7887_state *st = iio_priv(indio_dev);
s64 time_ns;
- __u8 *buf;
int b_sent;
- unsigned int bytes = bitmap_weight(indio_dev->active_scan_mask,
- indio_dev->masklength) *
- st->chip_info->channel[0].scan_type.storagebits / 8;
-
- buf = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
- if (buf == NULL)
- goto done;
-
b_sent = spi_sync(st->spi, st->ring_msg);
if (b_sent)
goto done;
time_ns = iio_get_time_ns();
- memcpy(buf, st->data, bytes);
if (indio_dev->scan_timestamp)
- memcpy(buf + indio_dev->scan_bytes - sizeof(s64),
+ memcpy(st->data + indio_dev->scan_bytes - sizeof(s64),
&time_ns, sizeof(time_ns));
- iio_push_to_buffer(indio_dev->buffer, buf);
+ iio_push_to_buffer(indio_dev->buffer, st->data);
done:
- kfree(buf);
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
--
1.8.0
--
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