Messages in this thread | | | From | David Brownell <> | Subject | Re: Bugs in MMC [was: [Bug 10030] Suspend doesn't work when SD card is inserted] | Date | Mon, 3 Mar 2008 13:59:37 -0800 |
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On Monday 25 February 2008, Pierre Ossman wrote: > On Sun, 24 Feb 2008 10:33:34 -0500 (EST) > Alan Stern <stern@rowland.harvard.edu> wrote: > > > But even changing that won't solve the second issue, which is a genuine > > bug. There is a race between detect events and suspend events. The > > mmc_suspend_host() routine starts out by flushing the kmmcd workqueue > > before calling the host's suspend routine. So what happens if another > > detect event occurs in between? > > > > The idea is that host drivers shouldn't do that. Once they've called > mmc_suspend_host(), then they shouldn't be poking the MMC core in any > other way. None of this is of course properly documented. :/
Card insert/remove events can be system wake events though. Which makes that restriction impractical.
I think hosts need to be able to call mmc_detect_change() as soon as they see a stable signal. The MMC core can hold off handling that for a while, if it needs to wait until the code walking the device tree gets around to resuming that host. It's a lot more natural to hold off such stuff one time there than in N host drivers; especially since the MMC core already has such hold-off code.
- Dave
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