From: Jan Andersson <jan@gaisler.com>

When the spi_mpc83xx driver receives a tx_buf pointer which is NULL, it
only writes one zero filled word to the transmit register.  If the driver
expects to receive more than one word it will wait forever for a second
receive interrupt.  With this patch the controller will shift out zeroes
until all words have been received.

Signed-off-by: Jan Andersson <jan@gaisler.com>
Tested-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/spi/spi_mpc83xx.c |    7 ++-----
 1 files changed, 2 insertions(+), 5 deletions(-)

diff -puN drivers/spi/spi_mpc83xx.c~spi_mpc83xx-hang-fix drivers/spi/spi_mpc83xx.c
--- a/drivers/spi/spi_mpc83xx.c~spi_mpc83xx-hang-fix
+++ a/drivers/spi/spi_mpc83xx.c
@@ -384,11 +384,8 @@ irqreturn_t mpc83xx_spi_irq(s32 irq, voi
 
 	mpc83xx_spi->count -= 1;
 	if (mpc83xx_spi->count) {
-		if (mpc83xx_spi->tx) {
-			u32 word = mpc83xx_spi->get_tx(mpc83xx_spi);
-			mpc83xx_spi_write_reg(&mpc83xx_spi->base->transmit,
-					      word);
-		}
+		u32 word = mpc83xx_spi->get_tx(mpc83xx_spi);
+		mpc83xx_spi_write_reg(&mpc83xx_spi->base->transmit, word);
 	} else {
 		complete(&mpc83xx_spi->done);
 	}
_