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| author | Vernon Sauder <vernoninhand@gmail.com> | 2008-10-16 07:02:40 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-16 20:21:38 +0200 |
| commit | f9b90e39cbc5c4d6ef60022fd1f25d541df0aad1 (patch) | |
| tree | af043fc4e24a12447c7312ef9b246f24d619f6f7 /drivers/spi | |
| parent | mpc52xx_psc_spi: remove code associated with !CONFIG_PPC_MERGE (diff) | |
| download | linux-f9b90e39cbc5c4d6ef60022fd1f25d541df0aad1.tar.xz linux-f9b90e39cbc5c4d6ef60022fd1f25d541df0aad1.zip | |
spi: simplify spi_write_then_read()
Modify spi_write_then_read() to use one transfer. This speeds up all
callers, and is a minor code shrink.
Signed-off-by: Vernon Sauder <Vernon.Sauder@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi.c | 22 |
1 files changed, 8 insertions, 14 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 75e86865234c..2de6b0e72f3f 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -660,7 +660,7 @@ int spi_write_then_read(struct spi_device *spi, int status; struct spi_message message; - struct spi_transfer x[2]; + struct spi_transfer x; u8 *local_buf; /* Use preallocated DMA-safe buffer. We can't avoid copying here, @@ -671,15 +671,9 @@ int spi_write_then_read(struct spi_device *spi, return -EINVAL; spi_message_init(&message); - memset(x, 0, sizeof x); - if (n_tx) { - x[0].len = n_tx; - spi_message_add_tail(&x[0], &message); - } - if (n_rx) { - x[1].len = n_rx; - spi_message_add_tail(&x[1], &message); - } + memset(&x, 0, sizeof x); + x.len = n_tx + n_rx; + spi_message_add_tail(&x, &message); /* ... unless someone else is using the pre-allocated buffer */ if (!mutex_trylock(&lock)) { @@ -690,15 +684,15 @@ int spi_write_then_read(struct spi_device *spi, local_buf = buf; memcpy(local_buf, txbuf, n_tx); - x[0].tx_buf = local_buf; - x[1].rx_buf = local_buf + n_tx; + x.tx_buf = local_buf; + x.rx_buf = local_buf; /* do the i/o */ status = spi_sync(spi, &message); if (status == 0) - memcpy(rxbuf, x[1].rx_buf, n_rx); + memcpy(rxbuf, x.rx_buf + n_tx, n_rx); - if (x[0].tx_buf == buf) + if (x.tx_buf == buf) mutex_unlock(&lock); else kfree(local_buf); |