From: Justin Chen <justinpo...@gmail.com>

commit 4df3bea7f9d2ddd9ac2c29ba945c7c4db2def29c upstream.

Currently we set the tx/rx buffer to 0xff when NULL. This causes
problems with some spi slaves where 0xff is a valid command. Looking
at other drivers, the tx/rx buffer is usually set to 0x00 when NULL.
Following this convention solves the issue.

Fixes: fa236a7ef240 ("spi: bcm-qspi: Add Broadcom MSPI driver")
Signed-off-by: Justin Chen <justinpo...@gmail.com>
Signed-off-by: Kamal Dasu <kdasu.k...@gmail.com>
Cc: sta...@vger.kernel.org
Link: https://lore.kernel.org/r/20200420190853.45614-6-kdasu.k...@gmail.com
Signed-off-by: Mark Brown <broo...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/spi/spi-bcm-qspi.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -670,7 +670,7 @@ static void read_from_hw(struct bcm_qspi
                        if (buf)
                                buf[tp.byte] = read_rxram_slot_u8(qspi, slot);
                        dev_dbg(&qspi->pdev->dev, "RD %02x\n",
-                               buf ? buf[tp.byte] : 0xff);
+                               buf ? buf[tp.byte] : 0x0);
                } else {
                        u16 *buf = tp.trans->rx_buf;
 
@@ -678,7 +678,7 @@ static void read_from_hw(struct bcm_qspi
                                buf[tp.byte / 2] = read_rxram_slot_u16(qspi,
                                                                      slot);
                        dev_dbg(&qspi->pdev->dev, "RD %04x\n",
-                               buf ? buf[tp.byte] : 0xffff);
+                               buf ? buf[tp.byte / 2] : 0x0);
                }
 
                update_qspi_trans_byte_count(qspi, &tp,
@@ -733,13 +733,13 @@ static int write_to_hw(struct bcm_qspi *
        while (!tstatus && slot < MSPI_NUM_CDRAM) {
                if (tp.trans->bits_per_word <= 8) {
                        const u8 *buf = tp.trans->tx_buf;
-                       u8 val = buf ? buf[tp.byte] : 0xff;
+                       u8 val = buf ? buf[tp.byte] : 0x00;
 
                        write_txram_slot_u8(qspi, slot, val);
                        dev_dbg(&qspi->pdev->dev, "WR %02x\n", val);
                } else {
                        const u16 *buf = tp.trans->tx_buf;
-                       u16 val = buf ? buf[tp.byte / 2] : 0xffff;
+                       u16 val = buf ? buf[tp.byte / 2] : 0x0000;
 
                        write_txram_slot_u16(qspi, slot, val);
                        dev_dbg(&qspi->pdev->dev, "WR %04x\n", val);


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