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spi/i.mx: drain MXC SPI transfer buffer when probing device

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On the MX31litekit, the bootloader seems to communicate with the MC13783
PMIC chip before booting Linux. However, it does not flush all the
buffers properly after that, which makes the imx-spi driver read
bogus data when probing the MC13783.

Fix that by draining the SPI receive buffer on startup.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Daniel Mack 2009-11-19 19:01:42 +00:00 committed by Grant Likely
parent d33c861e71
commit ce1807b2e5
1 changed files with 8 additions and 0 deletions
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8
drivers/spi/spi_imx.c
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@ -44,6 +44,9 @@
#define MXC_CSPIINT 0x0c
#define MXC_RESET 0x1c
#define MX3_CSPISTAT 0x14
#define MX3_CSPISTAT_RR (1 << 3)
/* generic defines to abstract from the different register layouts */
#define MXC_INT_RR (1 << 0) /* Receive data ready interrupt */
#define MXC_INT_TE (1 << 1) /* Transmit FIFO empty interrupt */
@ -593,6 +596,11 @@ static int __init spi_imx_probe(struct platform_device *pdev)
if (!cpu_is_mx31() || !cpu_is_mx35())
writel(1, spi_imx->base + MXC_RESET);
/* drain receive buffer */
if (cpu_is_mx31() || cpu_is_mx35())
while (readl(spi_imx->base + MX3_CSPISTAT) & MX3_CSPISTAT_RR)
readl(spi_imx->base + MXC_CSPIRXDATA);
spi_imx->intctrl(spi_imx, 0);
ret = spi_bitbang_start(&spi_imx->bitbang);