mmcbr_tune
if (mmcbr_tune(dev, hs400) != 0) {
DEVMETHOD(mmcbr_tune, rtsx_mmcbr_tune),
DEVMETHOD(mmcbr_tune, sdhci_generic_tune),
DEVMETHOD(mmcbr_tune, sdhci_fsl_fdt_tune),
DEVMETHOD(mmcbr_tune, sdhci_generic_tune),
DEVMETHOD(mmcbr_tune, sdhci_generic_tune),