spi: omap2_mcspi PIO RX fix

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>

diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index 3cdab131c4a9a55a0bea4221f5eb31aa0408b9aa..ea61724ae2256fe33035f77e29cce9a0a67eb48a 100644 (file)
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -350,6 +350,7 @@ omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
                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 *spi, struct spi_transfer *xfer)
                                                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 *spi, struct spi_transfer *xfer)
                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 *spi, struct spi_transfer *xfer)
                                                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 *spi, struct spi_transfer *xfer)
                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 *spi, struct spi_transfer *xfer)
                                                word_len, *(rx - 1));
 #endif
                        }
-                       c -= 4;
                } while (c);
        }