[PATCH] spi/imx: select master mode for all channels

[grant.likely@secretlab.ca (Grant Likely)]

2011/2/15 Grant Likely <grant.likely@secretlab.ca>:
> On Tue, Feb 08, 2011 at 09:08:59PM +0100, Uwe Kleine-K?nig wrote:
>> From: Sascha Hauer <s.hauer@pengutronix.de>
>>
>> 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-K?nig <u.kleine-koenig@pengutronix.de>
>> ---
>> Hello,
>>
>> maybe one of our friends at Freescale can comment?
>
> Any feedback on this one? ?Or should I just merge it?

I've gone ahead and merged it.  I can pull it back out if anyone
complains though.

Thanks,

g.

>
> g.
>
>>
>> Best regards
>> Uwe
>>
>> ?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 1cf9d5f..69d6dba 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);
>> --
>> 1.7.2.3
>>
>>
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>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.