On 30 May 2018 at 11:54, Kai Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote: > Hi Alan, Ulf, > > [snipped] >>> >>> tsx_usb probe function. >>> If pm_suspend_ignore_children() is called in rtsx_usb, the parent can be >>> correctly woken up when a card gets plugged. >>> Realtek also confirmed that this device supports remote wakeup signaling. >> >> >> I agree with Ulf, you probably should not call >> pm_suspend_ignore_children(). > > > Thanks. I think it's not the right path to take. > > > [snipped] >>> >>> Right now I am trying to figure out how to let rtsx_usb (parent) tells >>> rtsx_usb_sdmmc (child, mmc host) to wake up mmc core. >>> Is an interrupt required here? >> >> >> No; all you have to do is make the resume routine in the rtsx_usb >> driver call pm_request_resume(the child mmc host device). That >> tells the PM core to create a workqueue entry which will do a runtime >> resume of the mmc host device. > > > I stripped out MMC_CAP_NEEDS_POLL, and use pm_request_resume(child) to > resume the child mmc host from parent device. > In the child's resume function, I use mmc_detect_change() to detect the card > successfully. This may work for the card detect case (but still has problems), but not for the card removal scenario. For example, what if the child is already runtime resumed, and a detect has just be run, finding out that there is no card. The following call to mmc_detect_change(), from the runtime resume callback may not be executed then. > But the child's suspend function never gets called without > MMC_CAP_NEEDS_POLL. Weird. Sure you didn't call pm_runtime_get(child) from the parent device driver instead of pm_request_resume() > How do I let MMC core knows that the card is gone when the USB card reader > doesn't support interrupt? So you are saying that the USB card reader (parent) is not able to detect when a card is removed, only when it's inserted? Is that's the case, then polling is needed. Perhaps what is needed is to use polling, but only when the mmc host has been runtime resumed. Kind regards Uffe -- 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
