staging:iio:ad799x: Preallocate sample buffer

Avoid allocating and freeing the sample buffer for each transfer. Instead
allocate it once when we start sampling. Also pre-compute the number of bytes we
need to transfer in the same way.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/staging/iio/adc/ad799x.h b/drivers/staging/iio/adc/ad799x.h
index 82e83bb..b51680c 100644 (file)
--- a/drivers/staging/iio/adc/ad799x.h
+++ b/drivers/staging/iio/adc/ad799x.h
@@ -106,6 +106,9 @@ struct ad799x_state {
        u16                             int_vref_mv;
        unsigned                        id;
        u16                             config;
+
+       u8                              *rx_buf;
+       unsigned int                    transfer_size;
 };
 
 /*

diff --git a/drivers/staging/iio/adc/ad799x_core.c b/drivers/staging/iio/adc/ad799x_core.c
index b751055..8dc97b3 100644 (file)
--- a/drivers/staging/iio/adc/ad799x_core.c
+++ b/drivers/staging/iio/adc/ad799x_core.c
@@ -104,6 +104,13 @@ static int ad7997_8_update_scan_mode(struct iio_dev *indio_dev,
 {
        struct ad799x_state *st = iio_priv(indio_dev);
 
+       kfree(st->rx_buf);
+       st->rx_buf = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
+       if (!st->rx_buf)
+               return -ENOMEM;
+
+       st->transfer_size = bitmap_weight(scan_mask, indio_dev->masklength) * 2;
+
        switch (st->id) {
        case ad7997:
        case ad7998:
@@ -665,6 +672,7 @@ static int ad799x_remove(struct i2c_client *client)
                regulator_disable(st->reg);
                regulator_put(st->reg);
        }
+       kfree(st->rx_buf);
        iio_device_free(indio_dev);
 
        return 0;

diff --git a/drivers/staging/iio/adc/ad799x_ring.c b/drivers/staging/iio/adc/ad799x_ring.c
index 2c5f384..c2ebae1 100644 (file)
--- a/drivers/staging/iio/adc/ad799x_ring.c
+++ b/drivers/staging/iio/adc/ad799x_ring.c
@@ -36,14 +36,9 @@ static irqreturn_t ad799x_trigger_handler(int irq, void *p)
        struct iio_dev *indio_dev = pf->indio_dev;
        struct ad799x_state *st = iio_priv(indio_dev);
        s64 time_ns;
-       __u8 *rxbuf;
        int b_sent;
        u8 cmd;
 
-       rxbuf = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
-       if (rxbuf == NULL)
-               goto out;
-
        switch (st->id) {
        case ad7991:
        case ad7995:
@@ -66,20 +61,17 @@ static irqreturn_t ad799x_trigger_handler(int irq, void *p)
        }
 
        b_sent = i2c_smbus_read_i2c_block_data(st->client,
-                       cmd, bitmap_weight(indio_dev->active_scan_mask,
-                                          indio_dev->masklength) * 2, rxbuf);
+                       cmd, st->transfer_size, st->rx_buf);
        if (b_sent < 0)
-               goto done;
+               goto out;
 
        time_ns = iio_get_time_ns();
 
        if (indio_dev->scan_timestamp)
-               memcpy(rxbuf + indio_dev->scan_bytes - sizeof(s64),
+               memcpy(st->rx_buf + indio_dev->scan_bytes - sizeof(s64),
                        &time_ns, sizeof(time_ns));
 
-       iio_push_to_buffers(indio_dev, rxbuf);
-done:
-       kfree(rxbuf);
+       iio_push_to_buffers(indio_dev, st->rx_buf);
 out:
        iio_trigger_notify_done(indio_dev->trig);