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

[Greg KH]

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

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@xxxxxxxxx>
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 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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