From: Jean-Christophe Lallemand

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
---
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

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