linux-kernel - [PATCH 7/7] spi: s3c64xx: Write to PACKET

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Date:	Tue, 18 Sep 2012 11:21:59 -0700
From:	Simon Glass <sjg@...omium.org>
To:	LKML <linux-kernel@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org
Cc:	"kgene.kim" <kgene.kim@...sung.com>,
	Ben Dooks <ben-linux@...ff.org>,
	Srinivas KANDAGATLA <srinivas.kandagatla@...com>,
	Simon Glass <sjg@...omium.org>
Subject: [PATCH 7/7] spi: s3c64xx: Write to PACKET_CNT after reset

The Exynos5 datasheet specifically says that a software reset of SPI
must be performed before writing to the PACKET_CNT register. Also,
the current code sometimes causes an extra transfer or two to be
performed.

Adjust the code slightly to fix this problem.

Test flashrom operation on snow.
See that SPI operation with ChromeOS EC is reliable now.

Signed-off-by: Simon Glass <sjg@...omium.org>
---
 drivers/spi/spi-s3c64xx.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index c34ef8f..3716825 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -213,7 +213,9 @@ static void flush_fifo(struct s3c64xx_spi_driver_data *sdd)
 	unsigned long loops;
 	u32 val;
 
-	writel(0, regs + S3C64XX_SPI_PACKET_CNT);
+	val = readl(regs + S3C64XX_SPI_CH_CFG);
+	val &= ~(S3C64XX_SPI_CH_RXCH_ON | S3C64XX_SPI_CH_TXCH_ON);
+	writel(val, regs + S3C64XX_SPI_CH_CFG);
 
 	val = readl(regs + S3C64XX_SPI_CH_CFG);
 	val |= S3C64XX_SPI_CH_SW_RST;
@@ -250,9 +252,7 @@ static void flush_fifo(struct s3c64xx_spi_driver_data *sdd)
 	val &= ~(S3C64XX_SPI_MODE_TXDMA_ON | S3C64XX_SPI_MODE_RXDMA_ON);
 	writel(val, regs + S3C64XX_SPI_MODE_CFG);
 
-	val = readl(regs + S3C64XX_SPI_CH_CFG);
-	val &= ~(S3C64XX_SPI_CH_RXCH_ON | S3C64XX_SPI_CH_TXCH_ON);
-	writel(val, regs + S3C64XX_SPI_CH_CFG);
+	writel(0, regs + S3C64XX_SPI_PACKET_CNT);
 }
 
 static void s3c64xx_spi_dmacb(void *data)
-- 
1.7.7.3

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