On 14/09/20 9:40 am, AKASHI Takahiro wrote: > Adrian, > > On Fri, Aug 21, 2020 at 05:09:01PM +0300, Adrian Hunter wrote: >> On 10/07/20 2:11 pm, Ben Chuang wrote: >>> From: AKASHI Takahiro <takahiro.aka...@linaro.org> >>> >>> sdhci_start_signal_voltage_switch() should be called only in UHS-I mode, >>> and not for UHS-II mode. >>> >>> Signed-off-by: Ben Chuang <ben.chu...@genesyslogic.com.tw> >>> Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org> >>> --- >>> drivers/mmc/host/sdhci.c | 7 ++++++- >>> 1 file changed, 6 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >>> index 5511649946b9..7f2537648a08 100644 >>> --- a/drivers/mmc/host/sdhci.c >>> +++ b/drivers/mmc/host/sdhci.c >>> @@ -2623,8 +2623,13 @@ int sdhci_start_signal_voltage_switch(struct >>> mmc_host *mmc, >>> /* >>> * Signal Voltage Switching is only applicable for Host Controllers >>> * v3.00 and above. >>> + * But for UHS2, the signal voltage is supplied by vdd2 which is >>> + * already 1.8v so no voltage switch required. >>> */ >>> - if (host->version < SDHCI_SPEC_300) >>> + if (host->version < SDHCI_SPEC_300 || >>> + (IS_ENABLED(CONFIG_MMC_SDHCI_UHS2) && >>> + host->version >= SDHCI_SPEC_400 && >>> + host->mmc->flags & MMC_UHS2_SUPPORT)) >> >> Please look at hooking ->start_signal_voltage_switch() instead > > Do you mean that you want every platform driver who wants to support UHS-II > to set NULL to start_signal_voltage_switch hook even if this hack is > platform agnostic?
No, I see UHS-II as a separate layer i.e. UHS-II host controller driver | | | v | sdhci-uhs2 e.g. sdhci_uhs2_start_signal_voltage_switch | | v v sdhci e.g. sdhci_start_signal_voltage_switch Most things should go through sdhci-uhs2 but not nessarily everything.
