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 buffer on startup.
Signed-off-by: Daniel Mack <dan...@caiaq.de>
Cc: David Brownell <dbrown...@users.sourceforge.net>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Sascha Hauer <s.ha...@pengutronix.de>
Cc: Uwe Kleine-König <u.kleine-koe...@pengutronix.de>
Cc: spi-devel-general@lists.sourceforge.net
---
drivers/spi/spi_imx.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/drivers/spi/spi_imx.c b/drivers/spi/spi_imx.c
index 89c22ef..a3894fd 100644
--- a/drivers/spi/spi_imx.c
+++ b/drivers/spi/spi_imx.c
@@ -42,8 +42,11 @@
#define MXC_CSPITXDATA 0x04
#define MXC_CSPICTRL 0x08
#define MXC_CSPIINT 0x0c
+#define MXC_CSPISTAT 0x14
#define MXC_RESET 0x1c
+#define MXC_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 +596,10 @@ 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 the buffer */
+ while (readl(spi_imx->base + MXC_CSPISTAT) & MXC_CSPISTAT_RR)
+ readl(spi_imx->base + MXC_CSPIRXDATA);
+
spi_imx->intctrl(spi_imx, 0);
ret = spi_bitbang_start(&spi_imx->bitbang);
--
1.6.5.2
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