diff options
| author | Jean-Christophe Lallemand <jcl@develtech.com> | 2008-11-12 13:27:00 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-11-12 17:17:17 -0800 |
| commit | 50d7d5bf3168db5d04566dd7ffb9a820e9fdf484 (patch) | |
| tree | 55eba6757e8068e2a85d886d99701118f73f9170 /drivers/spi | |
| parent | 79b92f2bab0dc5ac70e8391548f75ac3268426e4 (diff) | |
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 <haavard.skinnemoen@atmel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | 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 02f9320f3ef..8abae4ad0fa 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); |