mpc52xx_psc_spi: fix block transfer

commit 9a7867e1b34c3575e7e76a05c0c54c6edbdae2a4 upstream

The block transfer routine in the mpc52xx psc spi driver misinterpret
the datasheet.  According to the processor datasheet the chipselect is
held as long as the EOF is not written.

Theoretically blocks of any sizes can be transferred in this way.  The
old routine however writes an EOF after every word, which has the size
of size_of_word.  This makes the transfer slow.

Also fixed some duplicate code.

Signed-off-by: Luotao Fu <l.fu@pengutronix.de>
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>

diff --git a/drivers/spi/mpc52xx_psc_spi.c b/drivers/spi/mpc52xx_psc_spi.c
index 90729469d481dced3ae3e70d1c284df22e385acf..f200661c5661bd745cf154f922358b4177c9a4e3 100644 (file)
--- a/drivers/spi/mpc52xx_psc_spi.c
+++ b/drivers/spi/mpc52xx_psc_spi.c
@@ -148,7 +148,6 @@ static int mpc52xx_psc_spi_transfer_rxtx(struct spi_device *spi,
        unsigned rfalarm;
        unsigned send_at_once = MPC52xx_PSC_BUFSIZE;
        unsigned recv_at_once;
-       unsigned bpw = mps->bits_per_word / 8;
 
        if (!t->tx_buf && !t->rx_buf && t->len)
                return -EINVAL;
@@ -164,22 +163,15 @@ static int mpc52xx_psc_spi_transfer_rxtx(struct spi_device *spi,
                }
 
                dev_dbg(&spi->dev, "send %d bytes...\n", send_at_once);
-               if (tx_buf) {
-                       for (; send_at_once; sb++, send_at_once--) {
-                               /* set EOF flag */
-                               if (mps->bits_per_word
-                                               && (sb + 1) % bpw == 0)
-                                       out_8(&psc->ircr2, 0x01);
+               for (; send_at_once; sb++, send_at_once--) {
+                       /* set EOF flag before the last word is sent */
+                       if (send_at_once == 1)
+                               out_8(&psc->ircr2, 0x01);
+
+                       if (tx_buf)
                                out_8(&psc->mpc52xx_psc_buffer_8, tx_buf[sb]);
-                       }
-               } else {
-                       for (; send_at_once; sb++, send_at_once--) {
-                               /* set EOF flag */
-                               if (mps->bits_per_word
-                                               && ((sb + 1) % bpw) == 0)
-                                       out_8(&psc->ircr2, 0x01);
+                       else
                                out_8(&psc->mpc52xx_psc_buffer_8, 0);
-                       }
                }