[patch 64/73] spi: omap2_mcspi PIO RX fix

Greg KH
2008-02-07T00:27:43Z

[-- Attachment #1: spi-omap2_mcspi-pio-rx-fix.patch --]
[-- Type: text/plain, Size: 2263 bytes --]

2.6.23-stable review patch. If anyone has any objections, please let us know.
------------------
From: Kalle Valo <kalle.valo@nokia.com>

patch feed9bab7b14b77be8d796bcee95e2343fb82955 in mainline.

Before transmission of the last word in PIO RX_ONLY mode rx+tx mode
is enabled:

/* prevent last RX_ONLY read from triggering
* more word i/o: switch to rx+tx
*/
if (c == 0 && tx == NULL)
mcspi_write_cs_reg(spi,
OMAP2_MCSPI_CHCONF0, l);

But because c is decremented after the test, c will never be zero and
rx+tx will not be enabled. This breaks RX_ONLY mode PIO transfers.

Fix it by decrementing c in the beginning of the various I/O loops.

Signed-off-by: Kalle Valo <kalle.valo@nokia.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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/spi/omap2_mcspi.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -350,6 +350,7 @@ omap2_mcspi_txrx_pio(struct spi_device *
tx = xfer->tx_buf;

do {
+ c -= 1;
if (tx != NULL) {
if (mcspi_wait_for_reg_bit(chstat_reg,
OMAP2_MCSPI_CHSTAT_TXS) < 0) {
@@ -380,7 +381,6 @@ omap2_mcspi_txrx_pio(struct spi_device *
word_len, *(rx - 1));
#endif
}
- c -= 1;
} while (c);
} else if (word_len <= 16) {
u16 *rx;
@@ -389,6 +389,7 @@ omap2_mcspi_txrx_pio(struct spi_device *
rx = xfer->rx_buf;
tx = xfer->tx_buf;
do {
+ c -= 2;
if (tx != NULL) {
if (mcspi_wait_for_reg_bit(chstat_reg,
OMAP2_MCSPI_CHSTAT_TXS) < 0) {
@@ -419,7 +420,6 @@ omap2_mcspi_txrx_pio(struct spi_device *
word_len, *(rx - 1));
#endif
}
- c -= 2;
} while (c);
} else if (word_len <= 32) {
u32 *rx;
@@ -428,6 +428,7 @@ omap2_mcspi_txrx_pio(struct spi_device *
rx = xfer->rx_buf;
tx = xfer->tx_buf;
do {
+ c -= 4;
if (tx != NULL) {
if (mcspi_wait_for_reg_bit(chstat_reg,
OMAP2_MCSPI_CHSTAT_TXS) < 0) {
@@ -458,7 +459,6 @@ omap2_mcspi_txrx_pio(struct spi_device *
word_len, *(rx - 1));
#endif
}
- c -= 4;
} while (c);
}

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