linux-kernel - [PATCH v2] spi/pxa2xx: fix incorrect SW mode chipselect setting for BayTrail LPSS SPI

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Message-Id: <1402675045-22460-1-git-send-email-chiau.ee.chew@intel.com>
Date:	Fri, 13 Jun 2014 23:57:25 +0800
From:	Chew Chiau Ee <chiau.ee.chew@...el.com>
To:	Eric Miao <eric.y.miao@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Haojian Zhuang <haojian.zhuang@...il.com>,
	Mark Brown <broonie@...nel.org>
Cc:	Chew Chiau Ee <chiau.ee.chew@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linux-arm-kernel@...ts.infradead.org, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] spi/pxa2xx: fix incorrect SW mode chipselect setting for BayTrail LPSS SPI

From: Chew, Chiau Ee <chiau.ee.chew@...el.com>

It was observed that after module removal followed by insertion,
the SW mode chipselect is not properly set. Thus causing transfer
failure due to incorrect CS toggling.

Signed-off-by: Chew, Chiau Ee <chiau.ee.chew@...el.com>
---
 drivers/spi/spi-pxa2xx.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index a98df7e..fe79210 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -118,6 +118,7 @@ static void lpss_ssp_setup(struct driver_data *drv_data)
 	 */
 	orig = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
 
+	/* Test SPI_CS_CONTROL_SW_MODE bit enabling */
 	value = orig | SPI_CS_CONTROL_SW_MODE;
 	writel(value, drv_data->ioaddr + offset + SPI_CS_CONTROL);
 	value = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
@@ -126,10 +127,13 @@ static void lpss_ssp_setup(struct driver_data *drv_data)
 		goto detection_done;
 	}
 
-	value &= ~SPI_CS_CONTROL_SW_MODE;
+	orig = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
+
+	/* Test SPI_CS_CONTROL_SW_MODE bit disabling */
+	value = orig & ~SPI_CS_CONTROL_SW_MODE;
 	writel(value, drv_data->ioaddr + offset + SPI_CS_CONTROL);
 	value = readl(drv_data->ioaddr + offset + SPI_CS_CONTROL);
-	if (value != orig) {
+	if (value != (orig & ~SPI_CS_CONTROL_SW_MODE)) {
 		offset = 0x800;
 		goto detection_done;
 	}
-- 
1.7.4.4

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