[PATCH v2] mmc: sdhci-esdhc-imx: map unsupported driver type to Type B

[Ian Ray]

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 40 Ohm driver strength [1], SDHCI
correctly warns:

  mmc2: invalid driver type, default to driver type B

Hook ->set_ios() to map any driver type value outside of the SD-defined
range to default Type B, so that SDHCI always receives a valid 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.

[1] 'fixed-emmc-driver-type', see JESD84-B51 Table 206 and
    Documentation/devicetree/bindings/mmc/mmc-controller-common.yaml

Fixes: 5a52c5701a67 ("mmc: core: Fix host controller programming for fixed driver type")
Link: https://lore.kernel.org/all/20260926122908.866-1-ian.ray@xxxxxxxxxxxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ian Ray <ian.ray@xxxxxxxxxxxxxxxx>
---
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 | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 6ab59d3e346f..33f63c6dc8ce 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -1142,6 +1142,14 @@ static void esdhc_reset_tuning(struct sdhci_host *host)
 	}
 }
 
+static void sdhci_esdhc_imx_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	if (ios->drv_type > MMC_SET_DRIVER_TYPE_D)
+		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);
@@ -1949,6 +1957,11 @@ static int sdhci_esdhc_imx_probe(struct platform_device *pdev)
 		 */
 		host->mmc_host_ops.init_card = usdhc_init_card;
 
+		/*
+		 * Validate host driver type.
+		 */
+		host->mmc_host_ops.set_ios = sdhci_esdhc_imx_set_ios;
+
 		host->max_timeout_count = 0xF;
 	}
 
-- 
2.47.3