Hi Ohad, Am 28.12.2010 13:45, schrieb Ohad Ben-Cohen: > On Tue, Dec 28, 2010 at 1:25 PM, Arnd Hannemann <arnd@xxxxxxxxxx> wrote: >> On some boards card power is hard wired to the slot >> and active regardless of host controller state. > ... >> This was observed on AP4EVB with tmio_mmc and a b43 based >> SDIO card: >> http://marc.info/?l=linux-mmc&m=128854536521274&w=2 > > Do you mean that your card is always powered on regardless of > mmc_power_off() invocations ? Yes, it seems so. > I always wondered why SDIO runtime PM didn't work with your card, so > thanks for the follow up on this. > > That said, if you card can't be powered down, then it shouldn't be > MMC_CAP_POWER_OFF_CARD at all (which literally means that the card can > be powered down). > > And if it isn't MMC_CAP_POWER_OFF_CARD, then runtime PM will stay > disabled for the card, so the problem you describe can't happen. Even if the card is kept powered, when mmc_power_off() is called, the host controller will stop the SD bus clock. So I believe at least some power is saved this way and MMC_CAP_POWER_OFF_CARD makes sense? Thanks, Arnd -- 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
