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| author | Sascha Hauer <s.hauer@pengutronix.de> | 2011-02-08 21:08:59 +0100 |
|---|---|---|
| committer | Grant Likely <grant.likely@secretlab.ca> | 2011-02-15 15:10:11 -0700 |
| commit | f020c39e51b1ef8389d5cf38190d32f55ff9d556 (patch) | |
| tree | 8813281630a49f837b1ddbf8c3c181574d53300e /drivers/spi | |
| parent | 12e8b325f28a87ad006822d0561112c1751dfc9b (diff) | |
| download | lwn-f020c39e51b1ef8389d5cf38190d32f55ff9d556.tar.gz lwn-f020c39e51b1ef8389d5cf38190d32f55ff9d556.zip | |
spi/imx: select master mode for all channels
The hardware seems to have a race condition when the inactive
channels are in slave mode. We support master mode only, so
we can just switch all channels to master mode.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
[ukleinek: add more verbose comment about the race]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi_imx.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/spi/spi_imx.c b/drivers/spi/spi_imx.c index 1cf9d5faabf4..69d6dba67c19 100644 --- a/drivers/spi/spi_imx.c +++ b/drivers/spi/spi_imx.c @@ -174,7 +174,7 @@ static unsigned int spi_imx_clkdiv_2(unsigned int fin, #define SPI_IMX2_3_CTRL 0x08 #define SPI_IMX2_3_CTRL_ENABLE (1 << 0) #define SPI_IMX2_3_CTRL_XCH (1 << 2) -#define SPI_IMX2_3_CTRL_MODE(cs) (1 << ((cs) + 4)) +#define SPI_IMX2_3_CTRL_MODE_MASK (0xf << 4) #define SPI_IMX2_3_CTRL_POSTDIV_OFFSET 8 #define SPI_IMX2_3_CTRL_PREDIV_OFFSET 12 #define SPI_IMX2_3_CTRL_CS(cs) ((cs) << 18) @@ -253,8 +253,14 @@ static int __maybe_unused spi_imx2_3_config(struct spi_imx_data *spi_imx, { u32 ctrl = SPI_IMX2_3_CTRL_ENABLE, cfg = 0; - /* set master mode */ - ctrl |= SPI_IMX2_3_CTRL_MODE(config->cs); + /* + * The hardware seems to have a race condition when changing modes. The + * current assumption is that the selection of the channel arrives + * earlier in the hardware than the mode bits when they are written at + * the same time. + * So set master mode for all channels as we do not support slave mode. + */ + ctrl |= SPI_IMX2_3_CTRL_MODE_MASK; /* set clock speed */ ctrl |= spi_imx2_3_clkdiv(spi_imx->spi_clk, config->speed_hz); |