[U-Boot] [PATCH] MX28: SPI: Fix CTRL0 not being written at end of DMA transfer
Marek Vasut
marex at denx.de
Sat Sep 1 03:31:15 CEST 2012
> The final DMA descriptor doesn't properly write CTRL0 register
> during the DMA transfer. Properly write CTRL0 to make sure the
> transmission is complete.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Fabio Estevam <festevam at gmail.com>
> Cc: Otavio Salvador <otavio at ossystems.com.br>
> Cc: Stefano Babic <sbabic at denx.de>
!!
Please discard
> ---
> drivers/spi/mxs_spi.c | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
> index 168dbe4..5ee0ea1 100644
> --- a/drivers/spi/mxs_spi.c
> +++ b/drivers/spi/mxs_spi.c
> @@ -226,6 +226,7 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave
> *slave, uint32_t cache_data_count;
> int dmach;
> int tl;
> + int ret = 0;
>
> ALLOC_CACHE_ALIGN_BUFFER(struct mxs_dma_desc, desc, desc_count);
>
> @@ -302,12 +303,25 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave
> *slave, MXS_DMA_DESC_IRQ | MXS_DMA_DESC_DEC_SEM;
> if (flags & SPI_XFER_END) {
> ctrl0 &= ~SSP_CTRL0_LOCK_CS;
> - dp->cmd.pio_words[0] = ctrl0 | SSP_CTRL0_IGNORE_CRC;
> + ctrl0 |= SSP_CTRL0_IGNORE_CRC;
> + dp->cmd.pio_words[0] = ctrl0;
> }
> mxs_dma_desc_append(dmach, dp);
>
> if (mxs_dma_go(dmach))
> - return -EINVAL;
> + ret = -EINVAL;
> +
> + /*
> + * The DMA contains further hidden gems, like the last transfer
> + * not writing the CTRL0 PIO word properly. Write the PIO word
> + * directly here for proper operation. This issue was detected
> + * on S25FL064P chip by issuing:
> + *
> + * sf probe 2:0 ; sf read 0x42000000 0 0x800000 ; sf probe 2:0
> + *
> + * This resulted in garbled subsequent probe.
> + */
> + writel(ctrl0, &ssp_regs->hw_ssp_ctrl0_reg);
>
> /* The data arrived into DRAM, invalidate cache over them */
> if (!write) {
> @@ -315,7 +329,7 @@ static int mxs_spi_xfer_dma(struct mxs_spi_slave
> *slave, (uint32_t)(data + cache_data_count));
> }
>
> - return 0;
> + return ret;
> }
>
> int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
Best regards,
Marek Vasut
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