Dear Juha Lumme,
> On MX23 the XFER_LEN
XFER_COUNT ;-)
> part in CTRL0 register was improperly OR'd
... during construction of DMA descriptor chain. Instead of being freshly set.
> , and
> because of that too many characters
Bytes
> were being expected from SPI.
expected from SPI during the last DMA cycle.
> This caused a timeout (SSP_TIMEOUT) to happen in the last package
... during the processing of the last DMA descriptor ...
> in the
> DMA chain, and resulted into a corrupted read.
Write too, really ;-)
> This is a workaround for the problem
This is actually a correct fix for the issue.
> , by clearing the XFER_LEN bytes always
> before reading the new size for XFER_LEN.
before setting new XFER_COUNT into the ctrl0 field of DMA control transfer.
> Cc: Marek Vasut <ma...@denx.de>
> Cc: Fabio Estevam <fabio.este...@freescale.com>
> Cc: Shawn Guo <shawn....@linaro.org
> Signed-off-by: Juha Lumme <juha.lu...@gmail.com>
All but the commit message,
Acked-by: Marek Vasut <ma...@denx.de>
> ---
> 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;
Best regards,
Marek Vasut
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