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From: sjg@chromium.org (Simon Glass)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 7/7] spi: s3c64xx: Write to PACKET_CNT after reset
Date: Tue, 18 Sep 2012 11:21:59 -0700	[thread overview]
Message-ID: <1347992519-6904-8-git-send-email-sjg@chromium.org> (raw)
In-Reply-To: <1347992519-6904-1-git-send-email-sjg@chromium.org>

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@chromium.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

      parent reply	other threads:[~2012-09-18 18:21 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-18 18:21 [PATCH 0/7] Add support for Exynos5 ISP SPI ports Simon Glass
2012-09-18 18:21 ` [PATCH 1/7] PM / Domains: add generic function 'pm_genpd_of_add_device_by_name' Simon Glass
2012-09-18 18:21 ` [PATCH 2/7] spi: s3c64xx: Fix enum dma_data_direction warning Simon Glass
2012-09-18 18:21 ` [PATCH 3/7] spi: s3c64xx: Add support for ISP SPI ports Simon Glass
2012-09-18 18:21 ` [PATCH 4/7] spi: s3c64xx: Use jiffies instead of loops for timeout Simon Glass
2012-09-18 18:21 ` [PATCH 5/7] spi: s3c64xx: Allow use with SPI ports without dma Simon Glass
2012-09-18 18:21 ` [PATCH 6/7] spi: s3c64xx: Tidy up SPI chip select handling Simon Glass
2012-09-18 18:21 ` Simon Glass [this message]

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