From: Matthias Fuchs <matthias.fuchs@esd.eu>
Date: Sat, 14 Jan 2012 02:25:25 +0000 (+0000)
Subject: mx28: fix i.MX28 spi driver
X-Git-Tag: v2012.04-rc1~216
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=2638b50b18ad78c8fc0433c05270d3c7d62a6e03;p=u-boot

mx28: fix i.MX28 spi driver

The generic spi flash driver (drivers/mtd/spi/spi_flash.c) uses the
spi low level driver's spi_xfer() function with len=0 to deassert the
SPI flash' chip select. But the i.MX28 spi driver rejects this call
due to len=0.

This patch implements an exception for len=0 with the SPI_XFER_END
flag set. This results in an extra read with the chip select being
deasserted afterwards. There seems to be no way to deassert the signal
by hand.

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu>
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
---

diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
index 4c27fef3d1..adb9ca8ec8 100644
--- a/drivers/spi/mxs_spi.c
+++ b/drivers/spi/mxs_spi.c
@@ -129,9 +129,15 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 	int len = bitlen / 8;
 	const char *tx = dout;
 	char *rx = din;
-
-	if (bitlen == 0)
-		return 0;
+	char dummy;
+
+	if (bitlen == 0) {
+		if (flags & SPI_XFER_END) {
+			rx = &dummy;
+			len = 1;
+		} else
+			return 0;
+	}
 
 	if (!rx && !tx)
 		return 0;