From mboxrd@z Thu Jan 1 00:00:00 1970 From: juha.lumme@gmail.com (Juha Lumme) Date: Wed, 26 Dec 2012 14:01:28 +0900 Subject: [PATCH] mxs: spi: clear XFER_LEN in CTRL0 register during DMA Message-ID: <1356498088-31176-1-git-send-email-juha.lumme@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On MX23 the XFER_LEN part in CTRL0 register was improperly OR'd, and because of that too many characters were being expected from SPI. This caused a timeout (SSP_TIMEOUT) to happen in the last package in the DMA chain, and resulted into a corrupted read. This is a workaround for the problem, by clearing the XFER_LEN bytes always before reading the new size for XFER_LEN. Cc: Marek Vasut Cc: Fabio Estevam Cc: Shawn Guo --- drivers/spi/spi-mxs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c index 86dd04d..265c33f 100644 --- a/drivers/spi/spi-mxs.c +++ b/drivers/spi/spi-mxs.c @@ -241,6 +241,7 @@ 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_DATA_XFER | mxs_spi_cs_to_reg(cs); if (*first) @@ -256,8 +257,10 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, int cs, if ((sg_count + 1 == sgs) && *last) ctrl0 |= BM_SSP_CTRL0_IGNORE_CRC; - if (ssp->devid == IMX23_SSP) + if (ssp->devid == IMX23_SSP) { + ctrl0 &= ~BM_SSP_CTRL0_XFER_COUNT; ctrl0 |= min; + } dma_xfer[sg_count].pio[0] = ctrl0; dma_xfer[sg_count].pio[3] = min; -- 1.7.10.4