Commit ba486a2a authored Dec 26, 2012 by Juha Lumme Committed by Grant Likely Feb 05, 2013

mxs/spi: clear XFER_COUNT in ctrl0 field in DMA descriptor



On MX23 the XFER_COUNT part in ctrl0 field in DMA descriptor was
improperly OR'd during the construction of DMA descriptor chain, instead
of being freshly set.  Because of that too many bytes were being
expected from SPI during the last DMA cycle.  This caused a timeout
(SSP_TIMEOUT) to happen in the processing of the last DMA descriptor,
and thus reads and writes were failing.  This is a fix for the problem,
by clearing XFER_COUNT bytes in ctrl0 before setting the new XFER_COUNT
for DMA descriptor.

Signed-off-by: Juha Lumme <juha.lumme@gmail.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

parent f3b8a8ec

drivers/spi/spi-mxs.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -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;

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