Hi Ulf, I am working on adding signal voltage switch callback to the meson mmc driver. While testing, I noticed that a few cards fail to exit the busy state after the voltage switch. After tinkering with the driver a bit, I noticed that increasing the clock frequency from 400kHz to 1MHz solve the problem. Strange, isn't it ? I'm don't know MMC that much but is it possible that some card require a minimum operating frequency to enter UHS mode ? The simplified spec (Part 1 - Physical Layer) says that before CMD11, we should have had CMD41 (Init Command) . After CMD41, the card should be operating at Default Speed or SDR12. I believe that in both case, the frequency is "up to 25Mhz" ? This would be the maximum, but is there a minimum ? 400kHz seems pretty low compared to 25Mhz ... I hope you will able to shed light on this :) Best Regards jerome -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
