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From:   justinpopo6@gmail.com
To:     linux-spi@vger.kernel.org
Cc:     kdasu.kdev@gmail.com, bcm-kernel-feedback-list@broadcom.com,
        broonie@kernel.org, linux-kernel@vger.kernel.org,
        f.fainelli@gmail.com, Justin Chen <justinpopo6@gmail.com>
Subject: [PATCH] spi: bcm-qspi: when tx/rx buffer is NULL set to 0
Date:   Thu,  7 Feb 2019 12:47:27 -0800
Message-Id: <1549572447-45456-1-git-send-email-justinpopo6@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Justin Chen <justinpopo6@gmail.com>

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 <justinpopo6@gmail.com>
---
 drivers/spi/spi-bcm-qspi.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-bcm-qspi.c b/drivers/spi/spi-bcm-qspi.c
index 584bcb0..79456aa 100644
--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -681,7 +681,7 @@ static void read_from_hw(struct bcm_qspi *qspi, int slots)
 			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] : 0x00);
 		} else {
 			u16 *buf = tp.trans->rx_buf;
 
@@ -689,7 +689,7 @@ static void read_from_hw(struct bcm_qspi *qspi, int slots)
 				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] : 0x0000);
 		}
 
 		update_qspi_trans_byte_count(qspi, &tp,
@@ -744,13 +744,13 @@ static int write_to_hw(struct bcm_qspi *qspi, struct spi_device *spi)
 	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);
-- 
2.7.4