Re: [PATCH v3] mmc: sdhci-esdhc-imx: map unsupported driver type to Type B

[Bough Chen <haibo.chen@oss.nxp.com>]

On Wed, Oct 07, 2026 at 10:03:12AM +0300, Ian Ray wrote:
> Since commit 5a52c5701a67 ("mmc: core: Fix host controller programming
> for fixed driver type"), the eMMC driver strength is passed directly to
> mmc_set_driver_type(), which propagates the value through ios.drv_type
> all the way to sdhci_set_ios().  For value 4, SDHCI correctly warns:
> 
>   mmc2: invalid driver type, default to driver type B
> 
> The host driver type has no effect on this controller: esdhc_writew_le()
> never programs the driver-type field of SDHCI_HOST_CONTROL2.  Hook
> set_ios() and force drv_type to the always-valid Type B, so that SDHCI
> never sees an unsupported value.
> 
> Tested on i.MX8MP (usdhc3, eMMC in HS400) with
> `fixed-emmc-driver-type = <4>`: the warning is gone and the HS_TIMING
> register contains 0x43 as expected.
> 

Reviewed-by: Haibo Chen <haibo.chen@nxp.com>

Regards
Haibo Chen
> Fixes: 5a52c5701a67 ("mmc: core: Fix host controller programming for fixed driver type")
> Link: https://lore.kernel.org/all/20260926122908.866-1-ian.ray@gehealthcare.com/
> Cc: stable@vger.kernel.org
> Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
> Signed-off-by: Ian Ray <ian.ray@gehealthcare.com>
> ---
> v2 -> v3: Force drv_type to Type B unconditionally;
>           hook set_ios() for all esdhc variants, not only usdhc (since
>           the driver-type field is ignored in all variants);
>           reword comments.
> 
> v1 -> v2: Move fix from mmc core to sdhci-esdhc-imx driver per review
>           (see "Link:" above); always provide a valid host driver type.
> 
>  drivers/mmc/host/sdhci-esdhc-imx.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
> index 6ab59d3e346f..931e383748a9 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -1142,6 +1142,20 @@ static void esdhc_reset_tuning(struct sdhci_host *host)
>  	}
>  }
>  
> +static void sdhci_esdhc_imx_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> +{
> +	/*
> +	 * This controller has no driver-type control: esdhc_writew_le()
> +	 * discards the driver-type field when writing SDHCI_HOST_CONTROL2.
> +	 * The programmed value is therefore irrelevant, but SDHCI rejects
> +	 * non-SD values such as 4 (eMMC 40 ohm, from fixed-emmc-driver-type).
> +	 * Force an always-valid Type B.
> +	 */
> +	ios->drv_type = MMC_SET_DRIVER_TYPE_B;
> +
> +	sdhci_set_ios(mmc, ios);
> +}
> +
>  static void usdhc_init_card(struct mmc_host *mmc, struct mmc_card *card)
>  {
>  	struct sdhci_host *host = mmc_priv(mmc);
> @@ -1952,6 +1966,9 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
>  		host->max_timeout_count = 0xF;
>  	}
>  
> +	/* No SDHCI driver type control */
> +	host->mmc_host_ops.set_ios = sdhci_esdhc_imx_set_ios;
> +
>  	if (imx_data->socdata->flags & ESDHC_FLAG_MAN_TUNING)
>  		sdhci_esdhc_ops.platform_execute_tuning =
>  					esdhc_executing_tuning;
> -- 
> 2.47.3
>