[U-Boot] [PATCH] MX28: SPI: Fix CTRL0 not being written at end of DMA transfer

[Marek Vasut <marex@denx.de>]

> 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@denx.de>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: Otavio Salvador <otavio@ossystems.com.br>
> Cc: Stefano Babic <sbabic@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