On 15/11/19 1:07 PM, haibo.chen@xxxxxxx wrote:
> From: Haibo Chen <haibo.chen@xxxxxxx>
>
> 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@xxxxxxx>
> ---
> drivers/mmc/host/sdhci.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 68db86c1b4c9..1436cc9c5f82 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2361,6 +2361,7 @@ void sdhci_send_tuning(struct sdhci_host *host, u32 opcode)
> struct mmc_request mrq = {};
> unsigned long flags;
> u32 b = host->sdma_boundary;
> + u8 ctrl;
>
> spin_lock_irqsave(&host->lock, flags);
>
> @@ -2388,6 +2389,17 @@ void sdhci_send_tuning(struct sdhci_host *host, u32 opcode)
> */
> sdhci_writew(host, SDHCI_TRNS_READ, SDHCI_TRANSFER_MODE);
>
> +
> + /* DMA already disabled, so clear the DMA Select here.
> + * Otherwise, if use ADMA2, even disable DMA, some
> + * controllers like i.MX usdhc will still prefetch the
> + * ADMA script when send tuning command, which will cause
> + * IOMMU report lack of TLB mapping error
> + */
> + ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
> + ctrl &= ~SDHCI_CTRL_DMA_MASK;
Value zero is SDMA, so this does not look like a generic sdhci change. What
about doing it in sdhci-esdhc-imx.c before executing tuning?
> + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
> +
> sdhci_send_command(host, &cmd);
>
> host->cmd = NULL;
>
