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Date: Mon, 3 Nov 2008 12:24:57 +0100 From: Haavard Skinnemoen <haavard.skinnemoen@...el.com> To: David Brownell <david-b@...bell.net> Cc: spi-devel-general@...ts.sourceforge.net, linux-kernel@...r.kernel.org, Jean-Christophe Lallemand <jcl@...eltech.com>, Haavard Skinnemoen <haavard.skinnemoen@...el.com> Subject: [PATCH] atmel_spi: work-around required for new HW bug in AT91SAM9263 Rev.B SPI controller From: Jean-Christophe Lallemand <jcl@...eltech.com> 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 <haavard.skinnemoen@...el.com> --- drivers/spi/atmel_spi.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c index 02f9320..8abae4a 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); -- 1.5.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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