From bd6880477a3d73270edead88f4b806504998e5d8 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Mon, 5 Nov 2012 09:56:00 +0000 Subject: [PATCH] staging:iio:ad7887: Preallocate sample buffer 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 Signed-off-by: Jonathan Cameron --- 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 2e09e54fc9c5..71e50925e066 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 b39923bbeedc..f11925e62cdc 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; -- 2.30.2