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staging:iio:ad7298: Do not perform endianness conversion in buffered mode

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For buffered mode we do not want to perform endianness conversion in the kernel,
but rather offload it to user space, since it is not always required to do a
conversion at all. It also greatly simplifies the kernel code since no
post-processing has to be done and may allow future optimizations like streaming
data directly to a storage device or over the network via DMA.

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 2012-11-15 13:15:00 +00:00 committed by Jonathan Cameron
parent ec04cb048d
commit ca654638f2
3 changed files with 5 additions and 9 deletions
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2
drivers/staging/iio/adc/ad7298.h
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@ -48,7 +48,7 @@ struct ad7298_state {
* DMA (thus cache coherency maintenance) requires the * DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines. * transfer buffers to live in their own cache lines.
*/ */
unsigned short rx_buf[8] ____cacheline_aligned; unsigned short rx_buf[12] ____cacheline_aligned;
unsigned short tx_buf[2]; unsigned short tx_buf[2];
}; };

1
drivers/staging/iio/adc/ad7298_core.c
View File

@ -35,6 +35,7 @@
.sign = 'u', \ .sign = 'u', \
.realbits = 12, \ .realbits = 12, \
.storagebits = 16, \ .storagebits = 16, \
.endianness = IIO_BE, \
}, \ }, \
} }

11
drivers/staging/iio/adc/ad7298_ring.c
View File

@ -76,8 +76,7 @@ static irqreturn_t ad7298_trigger_handler(int irq, void *p)
struct iio_dev *indio_dev = pf->indio_dev; struct iio_dev *indio_dev = pf->indio_dev;
struct ad7298_state *st = iio_priv(indio_dev); struct ad7298_state *st = iio_priv(indio_dev);
s64 time_ns = 0; s64 time_ns = 0;
__u16 buf[16]; int b_sent;
int b_sent, i;
b_sent = spi_sync(st->spi, &st->ring_msg); b_sent = spi_sync(st->spi, &st->ring_msg);
if (b_sent) if (b_sent)
@ -85,15 +84,11 @@ static irqreturn_t ad7298_trigger_handler(int irq, void *p)
if (indio_dev->scan_timestamp) { if (indio_dev->scan_timestamp) {
time_ns = iio_get_time_ns(); time_ns = iio_get_time_ns();
memcpy((u8 *)buf + indio_dev->scan_bytes - sizeof(s64), memcpy((u8 *)st->rx_buf + indio_dev->scan_bytes - sizeof(s64),
&time_ns, sizeof(time_ns)); &time_ns, sizeof(time_ns));
} }
for (i = 0; i < bitmap_weight(indio_dev->active_scan_mask, iio_push_to_buffers(indio_dev, (u8 *)st->rx_buf);
indio_dev->masklength); i++)
buf[i] = be16_to_cpu(st->rx_buf[i]);
iio_push_to_buffers(indio_dev, (u8 *)buf);
done: done:
iio_trigger_notify_done(indio_dev->trig); iio_trigger_notify_done(indio_dev->trig);