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mx28: fix i.MX28 spi driver

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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>
This commit is contained in:
Matthias Fuchs 2012-01-14 02:25:25 +00:00 committed by Albert ARIBAUD
parent 82182720e7
commit 2638b50b18
1 changed files with 8 additions and 2 deletions
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10
drivers/spi/mxs_spi.c
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@ -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;
char dummy;
if (bitlen == 0)
return 0;
if (bitlen == 0) {
if (flags & SPI_XFER_END) {
rx = &dummy;
len = 1;
} else
return 0;
}
if (!rx && !tx)
return 0;