[PATCH] spi_mpc8xxx: fix buffer overrun when sending only/receiving only more than PAGE_SIZE bytes

[christophe leroy]

This patch applies to 2.6.34.7 and 2.6.35.4
It fixes an issue when sending only or receiving only more than PAGE_SIZE bytes

Signed-off-by: christophe leroy <christophe.leroy at c-s.fr>

diff -urN c/drivers/spi/spi_mpc8xxx.c d/drivers/spi/spi_mpc8xxx.c
--- c/drivers/spi/spi_mpc8xxx.c	2010-09-08 16:44:03.000000000 +0200
+++ d/drivers/spi/spi_mpc8xxx.c	2010-09-08 16:44:14.000000000 +0200
@@ -393,11 +393,17 @@
 
 	xfer_ofs = mspi->xfer_in_progress->len - mspi->count;
 
-	out_be32(&rx_bd->cbd_bufaddr, mspi->rx_dma + xfer_ofs);
+	if (mspi->rx_dma == mspi->dma_dummy_rx)
+		out_be32(&rx_bd->cbd_bufaddr, mspi->rx_dma);
+	else
+		out_be32(&rx_bd->cbd_bufaddr, mspi->rx_dma + xfer_ofs);
 	out_be16(&rx_bd->cbd_datlen, 0);
 	out_be16(&rx_bd->cbd_sc, BD_SC_EMPTY | BD_SC_INTRPT | BD_SC_WRAP);
 
-	out_be32(&tx_bd->cbd_bufaddr, mspi->tx_dma + xfer_ofs);
+	if (mspi->tx_dma == mspi->dma_dummy_tx)
+		out_be32(&tx_bd->cbd_bufaddr, mspi->tx_dma);
+	else
+		out_be32(&tx_bd->cbd_bufaddr, mspi->tx_dma + xfer_ofs);
 	out_be16(&tx_bd->cbd_datlen, xfer_len);
 	out_be16(&tx_bd->cbd_sc, BD_SC_READY | BD_SC_INTRPT | BD_SC_WRAP |
 				 BD_SC_LAST);