On Mon, May 11, 2015 at 11:48 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > On 5 May 2015 at 18:03, Eliad Peller <eliad@xxxxxxxxxx> wrote: >> mmc_power_restore_host() calls mmc_power_up(), which >> returns immediately if power is already on. >> >> However, it still calls host->bus_ops->power_restore, >> which might result in various errors if the bus_ops >> doesn't handle it well (e.g. failing to run init >> sequence twice) >> >> Simply bail out in this case, without further calling >> bus_ops->power_restore. >> >> Specifically, this solves issue with wl18xx sdio card, >> where the mmc core powers on the card on resume (while >> MMC_PM_KEEP_POWER is not set), and the wl18xx device >> driver calls mmc_power_restore_host() once more. > > Could you elaborate on why that driver calls mmc_power_restore_host() > after the system PM suspend sequence? I am trying to understand the > use case. > The driver assumes control over the mmc power, in order to save power when no interface is up. It basically uses runtime_pm for it, but calls the power functions explicitly if pm_runtime returned non-zero (this is needed for some corner cases, e.g. runtime pm is disabled). On suspend (if wowlan is not configured), all the wlan interfaces are taken down, and the driver powers off the device. On resume, the interfaces are taken up again, and the driver powers on the device, by calling mmc_power_restore_host(). Eliad. -- 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
