From: Daniel Mack <daniel@caiaq.de>
To: linux-arm-kernel@lists.infradead.org
Cc: "David Brownell" <dbrownell@users.sourceforge.net>,
"Sascha Hauer" <s.hauer@pengutronix.de>,
"Daniel Mack" <daniel@caiaq.de>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
spi-devel-general@lists.sourceforge.net,
"Andrew Morton" <akpm@linux-foundation.org>
Subject: [PATCH] SPI: drain MXC SPI transfer buffer when probing device
Date: Thu, 19 Nov 2009 11:44:47 +0100 [thread overview]
Message-ID: <1258627487-7408-1-git-send-email-daniel@caiaq.de> (raw)
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 <daniel@caiaq.de>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Uwe Kleine-König <u.kleine-koenig@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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next reply other threads:[~2009-11-19 10:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-19 10:44 Daniel Mack [this message]
[not found] ` <1258627487-7408-1-git-send-email-daniel-rDUAYElUppE@public.gmane.org>
2009-11-19 18:49 ` [PATCH] SPI: drain MXC SPI transfer buffer when probing device Uwe Kleine-König
[not found] ` <20091119184951.GA26816-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2009-11-19 19:01 ` Daniel Mack
2009-11-19 19:08 ` Uwe Kleine-König
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