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authorTrent Piepho <tpiepho@gmail.com>2013-10-01 13:14:57 -0700
committerMark Brown <broonie@linaro.org>2013-10-18 01:00:30 +0100
commitdf23286e57ceefe427d7ff925193283a8fafe9f3 (patch)
tree86e495ed4b4e0494c952223cc8214bc97240045d /drivers/spi
parent28cad125881cb10172895774d4c3a04e748bf6bf (diff)
downloadlinux-df23286e57ceefe427d7ff925193283a8fafe9f3.tar.bz2
spi: spi-mxs: Fix extra CS pulses and read mode in multi-transfer messages
There are two bits which control the CS line in the CTRL0 register: LOCK_CS and IGNORE_CRC. The latter would be better named DEASSERT_CS in SPI mode. Setting DEASSERT_CS causes CS to be de-asserted at the end of the transfer. It should normally be set only for the final segment of the final transfer. The DMA code explicitly sets it in this case, but because it never clears the bit from the ctrl0 register, it will remain set for all transfers in subsequent messages. This results in a CS pulse between transfers. There is a similar problem with the read mode bit never being cleared in DMA mode. This patch fixes DEASSERT_CS and READ being left on in DMA mode. Signed-off-by: Trent Piepho <tpiepho@gmail.com> Cc: Marek Vasut <marex@denx.de> Cc: Fabio Estevam <fabio.estevam@freescale.com> Cc: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Mark Brown <broonie@linaro.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi-mxs.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index 090930aa7205..68ea5078a9cf 100644
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c
@@ -218,7 +218,8 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs,
INIT_COMPLETION(spi->c);
ctrl0 = readl(ssp->base + HW_SSP_CTRL0);
- ctrl0 &= ~BM_SSP_CTRL0_XFER_COUNT;
+ ctrl0 &= ~(BM_SSP_CTRL0_XFER_COUNT | BM_SSP_CTRL0_IGNORE_CRC |
+ BM_SSP_CTRL0_READ);
ctrl0 |= BM_SSP_CTRL0_DATA_XFER | mxs_spi_cs_to_reg(cs);
if (!(flags & TXRX_WRITE))