at 19:55, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
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.
I don't see this behavior though. May because I use mmc_detect_change()
directly in the runtime resume callback?
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()
I use pm_request_resume() here.
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?
Unfortunately yes. rtsx_usb keeps calling rtsx_usb_suspend() until there's
no card.
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.
Yes, I think this is exactly what I want. Is adding a new task to do the
polling ugly?
Kai-Heng
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
