On 11/05/2012 09:56 AM, Lars-Peter Clausen wrote:
> 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>
All 7 applied to togreg branch.
A nice series and good to get this one out of staging as it's
been pretty much clean for an awful long time!
Jonathan
p.s. I thought I had sent this the other day but it appears not!
> ---
> 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;
>
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