Re: [PATCH v3 13/14] mmc: sdhci-esdhc-imx: clear DMA_SEL when disable DMA mode

[Adrian Hunter <adrian.hunter@intel.com>]

On 10/02/20 10:49 am, haibo.chen@nxp.com wrote:
> From: Haibo Chen <haibo.chen@nxp.com>
> 
> Currently, when use standard tuning, driver default disable DMA just before
> send tuning command. But on i.MX8 usdhc, this is not enough. Need also clear
> DMA_SEL. If not, once the DMA_SEL select AMDA2 before, even dma already disabled,
> when send tuning command, usdhc will still prefetch the ADMA script from wrong
> DMA address, then we will see IOMMU report some error which show lack of TLB
> mapping.
> 
> Signed-off-by: Haibo Chen <haibo.chen@nxp.com>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  drivers/mmc/host/sdhci-esdhc-imx.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
> index dedc067cd0dd..44837e3014e8 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -639,10 +639,24 @@ static void esdhc_writew_le(struct sdhci_host *host, u16 val, int reg)
>  			 * For DMA access restore the levels to default value.
>  			 */
>  			m = readl(host->ioaddr + ESDHC_WTMK_LVL);
> -			if (val & SDHCI_TRNS_DMA)
> +			if (val & SDHCI_TRNS_DMA) {
>  				wml = ESDHC_WTMK_LVL_WML_VAL_DEF;
> -			else
> +			} else {
> +				u8 ctrl;
>  				wml = ESDHC_WTMK_LVL_WML_VAL_MAX;
> +
> +				/*
> +				 * Since already disable DMA mode, so also need
> +				 * to clear the DMASEL. Otherwise, for standard
> +				 * tuning, when send tuning command, usdhc will
> +				 * still prefetch the ADMA script from wrong
> +				 * DMA address, then we will see IOMMU report
> +				 * some error which show lack of TLB mapping.
> +				 */
> +				ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
> +				ctrl &= ~SDHCI_CTRL_DMA_MASK;
> +				sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
> +			}
>  			m &= ~(ESDHC_WTMK_LVL_RD_WML_MASK |
>  			       ESDHC_WTMK_LVL_WR_WML_MASK);
>  			m |= (wml << ESDHC_WTMK_LVL_RD_WML_SHIFT) |
>