diff options
| author | Lars-Peter Clausen <lars@metafoo.de> | 2012-09-10 09:34:00 +0100 |
|---|---|---|
| committer | Jonathan Cameron <jic23@kernel.org> | 2012-09-13 20:25:49 +0100 |
| commit | 93e33d703030fe0348c1ff9d8f40bc6c2d82dc30 (patch) | |
| tree | d413d688dc86f19ead5f8b24b91d8ea5153fb6c2 | |
| parent | fcc7800b652e55420b85d1c885f39e8a230ace59 (diff) | |
staging:iio:ad7476: Avoid alloc/free for each sample in buffered mode
The ad7476 driver has only support for 1 channel ADCs. So the upper limit for
the buffer size is the size of one sample plus the size of the timestamp.
Preallocate a buffer large enough to hold this to avoid having to allocate and
free a new buffer for each sample being captured.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
| -rw-r--r-- | drivers/staging/iio/adc/ad7476.h | 5 | ||||
| -rw-r--r-- | drivers/staging/iio/adc/ad7476_ring.c | 14 |
2 files changed, 7 insertions, 12 deletions
diff --git a/drivers/staging/iio/adc/ad7476.h b/drivers/staging/iio/adc/ad7476.h index 6085fad21165..c4f11509920a 100644 --- a/drivers/staging/iio/adc/ad7476.h +++ b/drivers/staging/iio/adc/ad7476.h @@ -33,8 +33,11 @@ struct ad7476_state { /* * DMA (thus cache coherency maintenance) requires the * transfer buffers to live in their own cache lines. + * Make the buffer large enough for one 16 bit sample and one 64 bit + * aligned 64 bit timestamp. */ - unsigned char data[2] ____cacheline_aligned; + unsigned char data[ALIGN(2, sizeof(s64)) + sizeof(s64)] + ____cacheline_aligned; }; enum ad7476_supported_device_ids { diff --git a/drivers/staging/iio/adc/ad7476_ring.c b/drivers/staging/iio/adc/ad7476_ring.c index 940681f29b87..3c869b05f209 100644 --- a/drivers/staging/iio/adc/ad7476_ring.c +++ b/drivers/staging/iio/adc/ad7476_ring.c @@ -26,28 +26,20 @@ static irqreturn_t ad7476_trigger_handler(int irq, void *p) struct iio_dev *indio_dev = pf->indio_dev; struct ad7476_state *st = iio_priv(indio_dev); s64 time_ns; - __u8 *rxbuf; int b_sent; - rxbuf = kzalloc(indio_dev->scan_bytes, GFP_KERNEL); - if (rxbuf == NULL) - goto done; - - b_sent = spi_read(st->spi, rxbuf, - st->chip_info->channel[0].scan_type.storagebits / 8); + b_sent = spi_sync(st->spi, &st->msg); if (b_sent < 0) goto done; time_ns = iio_get_time_ns(); if (indio_dev->scan_timestamp) - memcpy(rxbuf + indio_dev->scan_bytes - sizeof(s64), - &time_ns, sizeof(time_ns)); + ((s64 *)st->data)[1] = time_ns; - iio_push_to_buffer(indio_dev->buffer, rxbuf); + iio_push_to_buffer(indio_dev->buffer, st->data); done: iio_trigger_notify_done(indio_dev->trig); - kfree(rxbuf); return IRQ_HANDLED; } |