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Commit f020c39e authored by Sascha Hauer's avatar Sascha Hauer Committed by Grant Likely
Browse files

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: default avatarSascha Hauer <s.hauer@pengutronix.de>
[ukleinek: add more verbose comment about the race]
Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 12e8b325

drivers/spi/spi_imx.c

+9 −3
Original line number Diff line number Diff line
@@ -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);