The patch titled
spi: simplify spi_write_then_read()
has been added to the -mm tree. Its filename is
spi-simplify-spi_write_then_read.patch
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------------------------------------------------------
Subject: spi: simplify spi_write_then_read()
From: Vernon Sauder <vernoninhand@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/spi/spi.c | 22 ++++++++--------------
1 file changed, 8 insertions(+), 14 deletions(-)
diff -puN drivers/spi/spi.c~spi-simplify-spi_write_then_read drivers/spi/spi.c
--- a/drivers/spi/spi.c~spi-simplify-spi_write_then_read
+++ a/drivers/spi/spi.c
@@ -660,7 +660,7 @@ int spi_write_then_read(struct spi_devic
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_devic
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_devic
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);
_
Patches currently in -mm which might be from vernoninhand@xxxxxxxxx are
spi-simplify-spi_write_then_read.patch
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