570 	 * while HS400 tuning is in progress we end up with mismatched driver  in amd_select_drive_strength()
571 	 * strengths between the controller and the card. HS400 tuning requires  in amd_select_drive_strength()
572 	 * switching from HS400->DDR52->HS->HS200->HS400. So the driver mismatch  in amd_select_drive_strength()
580 	 * card's timing to HS200 or HS400. The card will use the default driver  in amd_select_drive_strength()
601  * The initialization sequence for HS400 is:
602  *     HS->HS200->Perform Tuning->HS->HS400
605  *     HS400->DDR52->HS->HS200->Perform Tuning->HS->HS400
607  * The AMD eMMC Controller can only use the tuned clock while in HS200 and HS400
610  * HS400, we can re-enable the tuned clock.
635 		/* DLL is only required for HS400 */  in amd_set_ios()
705 	 *    b) The HS200 and HS400 driver strengths don't match.  in sdhci_acpi_emmc_amd_probe_slot()
707 	 *       A, but the (internal) HS400 preset register has a driver  in sdhci_acpi_emmc_amd_probe_slot()
708 	 *       strength of B. As part of initializing HS400, HS200 tuning  in sdhci_acpi_emmc_amd_probe_slot()
715 	 *    HS400 preset driver strengths match.  in sdhci_acpi_emmc_amd_probe_slot()
717 	 *    Enabling presets for HS400 doesn't work for the following reasons:  in sdhci_acpi_emmc_amd_probe_slot()
721 	 *       read out HS400 presets. The AMD controller doesn't support this  in sdhci_acpi_emmc_amd_probe_slot()
722 	 *       non-standard register. In fact, it doesn't expose the HS400  in sdhci_acpi_emmc_amd_probe_slot()
726 	 *       Since HS400 and HS200 presets must be identical, we could  in sdhci_acpi_emmc_amd_probe_slot()