Messages in this thread | | | Date | Fri, 12 Jul 2013 10:37:33 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH] PM: avoid 'autosleep' in shutdown progress |
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On Fri, 12 Jul 2013, Yanmin Zhang wrote:
> On Thu, 2013-07-11 at 16:03 +0800, shuox.liu@intel.com wrote: > > From: Liu ShuoX <shuox.liu@intel.com> > > > > In shutdown progress, system is possible to do power transition > > (such as suspend-to-ram) in parallel. It is unreasonable. So, > > fixes it by adding a system_state checking and queue try_to_suspend > > again when system status is not running. > > > > Signed-off-by: Liu ShuoX <shuox.liu@intel.com> > > --- > > kernel/power/autosleep.c | 3 ++- > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > Without this patch, we hit an hang issue on Android. > > Scenario: > Kernel starts shutdown and calls all device driver's shutdown callback. > When a driver's shutdown is called, the last wakelock is released and > suspend-to-ram starts. However, as some driver's shut down callbacks > already shut down devices and disable runtime pm, the suspend-to-ram > calls driver's suspend callback without noticing that device is already > off and causes crash. > We know the drivers should be fixed, but can we also change generic > codes a little to make it stronger?
Indeed, this does seem like the sort of thing we want to have. Allowing an "automatic" or "opportunistic" sleep in the middle of a shutdown makes no sense at all. In fact, it might be a good idea to disable system sleep completely at this time -- not even a write to /sys/power/state should be allowed to interrupt a shutdown.
Alan Stern
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