Hi Matthias,
On Sat, Jan 14, 2012 at 10:25 AM, Matthias Fuchs <matthias.fu...@esd.eu> wrote:
> 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>
What about the approach bellow (untested)?
--- a/drivers/spi/mxs_spi.c
+++ b/drivers/spi/mxs_spi.c
@@ -126,17 +126,14 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
{
struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave);
struct mx28_ssp_regs *ssp_regs = mxs_slave->regs;
- int len = bitlen / 8;
+ unsigned int len = bitlen / 8;
const char *tx = dout;
char *rx = din;
- if (bitlen == 0)
- return 0;
-
if (!rx && !tx)
return 0;
- if (flags & SPI_XFER_BEGIN)
+ if ((flags & SPI_XFER_BEGIN) && !len)
mxs_spi_start_xfer(ssp_regs);
while (len--) {
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