From ce1807b2e527979bd77d8a1a1768a6365f3febb5 Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Thu, 19 Nov 2009 19:01:42 +0000 Subject: [PATCH] spi/i.mx: drain MXC SPI transfer buffer when probing device MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Acked-by: Uwe Kleine-König Signed-off-by: Grant Likely --- drivers/spi/spi_imx.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/spi/spi_imx.c b/drivers/spi/spi_imx.c index 89c22efedfb0..1b17f443dee7 100644 --- a/drivers/spi/spi_imx.c +++ b/drivers/spi/spi_imx.c @@ -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); -- 2.20.1