From 50d7d5bf3168db5d04566dd7ffb9a820e9fdf484 Mon Sep 17 00:00:00 2001 From: Jean-Christophe Lallemand Date: Wed, 12 Nov 2008 13:27:00 -0800 Subject: [PATCH] atmel_spi: work-around required for new HW bug in AT91SAM9263 Rev.B SPI controller We're working with an AT91SAM9263 Rev B in our design and I experienced some inconsistency in spi-based touchscreen usage between our board and the Atmel evaluation kit we have that runs on a Rev A chip. The data was apparently delayed by 1 byte and got ridiculous data out of the touchscreen driver, very strange. As everything looked normal in the spi, touchscreen and dma logs, I contacted the Atmel support and they triggered me on a new HW bug that appeared in the Rev B SPI controller. The problem is that the SPI controller on the Rev B needs that the software reset is performed two times so that it's performed correctly. Applying the patch below solves the issue on my Rev B board. I've tested it as well on my Rev A evaluation kit and it has apparently no unwanted side effect, things continue to work as expected. Signed-off-by: Haavard Skinnemoen Cc: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/spi/atmel_spi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c index 02f9320f3efc..8abae4ad0fa5 100644 --- a/drivers/spi/atmel_spi.c +++ b/drivers/spi/atmel_spi.c @@ -766,6 +766,7 @@ static int __init atmel_spi_probe(struct platform_device *pdev) /* Initialize the hardware */ clk_enable(clk); spi_writel(as, CR, SPI_BIT(SWRST)); + spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */ spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS)); spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS)); spi_writel(as, CR, SPI_BIT(SPIEN)); @@ -782,6 +783,7 @@ static int __init atmel_spi_probe(struct platform_device *pdev) out_reset_hw: spi_writel(as, CR, SPI_BIT(SWRST)); + spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */ clk_disable(clk); free_irq(irq, master); out_unmap_regs: @@ -805,6 +807,7 @@ static int __exit atmel_spi_remove(struct platform_device *pdev) spin_lock_irq(&as->lock); as->stopping = 1; spi_writel(as, CR, SPI_BIT(SWRST)); + spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */ spi_readl(as, SR); spin_unlock_irq(&as->lock);