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spi: Fix handling of cs_change in core implementation

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The core implementation of cs_change didn't follow the documentation
which says that cs_change in the middle of the transfer means to briefly
deassert chip select, instead it followed buggy drivers which change the
polarity of chip select.  Use a delay of 10us between deassert and
reassert simply from pulling numbers out of a hat.

Reported-by: Gerhard Sittig <gsi@denx.de>
Signed-off-by: Mark Brown <broonie@linaro.org>
This commit is contained in:
Mark Brown 2014-03-29 23:48:07 +00:00
parent 38dbfb59d1
commit 0b73aa63c1
1 changed files with 3 additions and 3 deletions
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6
drivers/spi/spi.c
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@ -591,7 +591,6 @@ static int spi_transfer_one_message(struct spi_master *master,
struct spi_message *msg)
{
struct spi_transfer *xfer;
bool cur_cs = true;
bool keep_cs = false;
int ret = 0;
@ -627,8 +626,9 @@ static int spi_transfer_one_message(struct spi_master *master,
&msg->transfers)) {
keep_cs = true;
} else {
cur_cs = !cur_cs;
spi_set_cs(msg->spi, cur_cs);
spi_set_cs(msg->spi, false);
udelay(10);
spi_set_cs(msg->spi, true);
}
}