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.fu...@esd.eu>
---
drivers/spi/mxs_spi.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
index 4c27fef..adb9ca8 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;
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