mmc: core: Drop HS400 caps unless 8-bit bus is supported too

When mmc_select_hs400es() tries to switch to the HS400 ES mode, it may bail
out early if the host doesn't support an 8-bit buswidth, as it's required
for the HS400 mode.

To improve the situation, let's instead drop the HS400 bits from the
capability field if the 8-bit bus isn't supported. In this way, we allow
the mmc initialization to continue by trying a lower speed mode.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20220303165151.129806-1-ulf.hansson@linaro.org

drivers/mmc/core/host.c

@@ -590,11 +590,20 @@ EXPORT_SYMBOL(mmc_alloc_host);
 
 static int mmc_validate_host_caps(struct mmc_host *host)
 {
-	if (host->caps & MMC_CAP_SDIO_IRQ && !host->ops->enable_sdio_irq) {
-		dev_warn(host->parent, "missing ->enable_sdio_irq() ops\n");
+	struct device *dev = host->parent;
+	u32 caps = host->caps, caps2 = host->caps2;
+
+	if (caps & MMC_CAP_SDIO_IRQ && !host->ops->enable_sdio_irq) {
+		dev_warn(dev, "missing ->enable_sdio_irq() ops\n");
 		return -EINVAL;
 	}
 
+	if (caps2 & (MMC_CAP2_HS400_ES | MMC_CAP2_HS400) &&
+	    !(caps & MMC_CAP_8_BIT_DATA)) {
+		dev_warn(dev, "drop HS400 support since no 8-bit bus\n");
+		host->caps2 = caps2 & ~MMC_CAP2_HS400_ES & ~MMC_CAP2_HS400;
+	}
+
 	return 0;
 }
 

drivers/mmc/core/mmc.c

@@ -1355,11 +1355,6 @@ static int mmc_select_hs400es(struct mmc_card *card)
 	int err = -EINVAL;
 	u8 val;
 
-	if (!(host->caps & MMC_CAP_8_BIT_DATA)) {
-		err = -ENOTSUPP;
-		goto out_err;
-	}
-
 	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400_1_2V)
 		err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120);