Index: sys/dev/sdhci/sdhci.c
===================================================================
--- sys/dev/sdhci/sdhci.c
+++ sys/dev/sdhci/sdhci.c
@@ -989,7 +989,7 @@
 		host_caps |= MMC_CAP_DRIVER_TYPE_C;
 	if (caps2 & SDHCI_CAN_DRIVE_TYPE_D)
 		host_caps |= MMC_CAP_DRIVER_TYPE_D;
-	slot->host.caps = host_caps;
+	slot->host.caps |= host_caps;
 
 	/* Decide if we have usable DMA. */
 	if (caps & SDHCI_CAN_DO_DMA)
Index: sys/dev/sdhci/sdhci_acpi.c
===================================================================
--- sys/dev/sdhci/sdhci_acpi.c
+++ sys/dev/sdhci/sdhci_acpi.c
@@ -45,12 +45,15 @@
 #include <dev/acpica/acpivar.h>
 
 #include <dev/mmc/bridge.h>
+#include <dev/mmc/mmcreg.h>
 
 #include <dev/sdhci/sdhci.h>
 
 #include "mmcbr_if.h"
 #include "sdhci_if.h"
 
+#define	SDHCI_AMD_RESET_DLL_REGISTER	0x908
+
 static const struct sdhci_acpi_device {
 	const char*	hid;
 	int		uid;
@@ -277,6 +280,10 @@
 	sc->quirks |= sdhci_quirk_set;
 	sc->slot.quirks = sc->quirks;
 
+	if (strcmp(acpi_dev->hid, "AMDI0040") == 0 &&
+		acpi_dev->uid == 0) {
+		sc->slot.host.caps |= MMC_CAP_MMC_HS400;
+	}
 	err = sdhci_init_slot(dev, &sc->slot, 0);
 	if (err) {
 		device_printf(dev, "failed to init slot\n");
@@ -360,6 +367,52 @@
 	sdhci_generic_intr(&sc->slot);
 }
 
+static inline void
+sdhci_acpi_amd_reset_dll(struct sdhci_slot *slot)
+{
+	sdhci_acpi_write_4(slot->bus, slot, SDHCI_AMD_RESET_DLL_REGISTER,
+		0x40003210);
+	DELAY(20);
+	sdhci_acpi_write_4(slot->bus, slot, SDHCI_AMD_RESET_DLL_REGISTER,
+		0x40033210);
+}
+
+static void
+sdhci_acpi_set_uhs_timing(device_t dev, struct sdhci_slot *slot)
+{
+	const struct sdhci_acpi_device *acpi_dev;
+	struct mmc_ios *ios;
+	uint16_t old_timing;
+	uint16_t hostctrl2;
+
+	acpi_dev = sdhci_acpi_find_device(dev);
+	if (acpi_dev == NULL)
+		return;
+
+	ios = &slot->host.ios;
+	old_timing = sdhci_acpi_read_2(slot->bus, slot, SDHCI_HOST_CONTROL2);
+	old_timing &= SDHCI_CTRL2_UHS_MASK;
+	sdhci_generic_set_uhs_timing(dev, slot);
+
+	if (strcmp(acpi_dev->hid,"AMDI0040") == 0 &&
+		acpi_dev->uid == 0) {
+		if (old_timing == SDHCI_CTRL2_UHS_SDR104 &&
+			ios->timing == bus_timing_hs) {
+			hostctrl2 = sdhci_acpi_read_2(slot->bus, slot, SDHCI_HOST_CONTROL2);
+			sdhci_acpi_write_2(slot->bus, slot, SDHCI_HOST_CONTROL2, hostctrl2 &
+				 ~SDHCI_CTRL2_SAMPLING_CLOCK);
+		}
+		if (ios->clock > SD_SDR50_MAX &&
+			old_timing != SDHCI_CTRL2_MMC_HS400 &&
+			ios->timing == bus_timing_mmc_hs400) {
+			hostctrl2 = sdhci_acpi_read_2(slot->bus, slot, SDHCI_HOST_CONTROL2);
+			sdhci_acpi_write_2(slot->bus, slot, SDHCI_HOST_CONTROL2, hostctrl2 |
+				 SDHCI_CTRL2_SAMPLING_CLOCK);
+			sdhci_acpi_amd_reset_dll(slot);
+		}
+	}
+}
+
 static device_method_t sdhci_methods[] = {
 	/* device_if */
 	DEVMETHOD(device_probe, sdhci_acpi_probe),
@@ -392,7 +445,7 @@
 	DEVMETHOD(sdhci_write_2,	sdhci_acpi_write_2),
 	DEVMETHOD(sdhci_write_4,	sdhci_acpi_write_4),
 	DEVMETHOD(sdhci_write_multi_4,	sdhci_acpi_write_multi_4),
-	DEVMETHOD(sdhci_set_uhs_timing,	sdhci_generic_set_uhs_timing),
+	DEVMETHOD(sdhci_set_uhs_timing,	sdhci_acpi_set_uhs_timing),
 
 	DEVMETHOD_END
 };