Hi, On Tuesday 10 July 2018 05:05 PM, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > Commit 52cdbdd49853 (driver core: correct device's shutdown order) > introduced a regression by breaking device shutdown on some systems. > > Namely, the devices_kset_move_last() call in really_probe() added by > that commit is a mistake as it may cause parents to follow children > in the devices_kset list which then causes shutdown to fail. For > example, if a device has children before really_probe() is called > for it (which is not uncommon), that call will cause it to be > reordered after the children in the devices_kset list and the > ordering of that list will not reflect the correct device shutdown > order any more. > > Also it causes the devices_kset list to be constantly reordered > until all drivers have been probed which is totally pointless > overhead in the majority of cases and it only covers an issue > with system shutdown, while system-wide suspend/resume potentially > has the same issue on the affected platforms (which is not covered). > > For that reason, revert the really_probe() modifications made by > commit 52cdbdd49853 which unfortunately will expose the shutdown > issue the problematic commit attempted to fix (and which will have > to be addressed differently and correctly in the future). > > The other code changes made by commit 52cdbdd49853 are useful and > they need not be reverted. > > Fixes: 52cdbdd49853 (driver core: correct device's shutdown order) > Link: https://lore.kernel.org/lkml/CAFgQCTt7VfqM=UyCnvNFxrSw8Z6cUtAi3HUwR4_xPAc03SgHjQ@xxxxxxxxxxxxxx/ > Reported-by: Pingfan Liu <kernelfans@xxxxxxxxx> > Tested-by: Pingfan Liu <kernelfans@xxxxxxxxx> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > --- This issue because of which 52cdbdd49853 (driver core: correct device's shutdown order) was added is not present from 4.18, since dra7 started using sdhci-omap.c driver which doesn't disable regulator during shutdown. (The original issue was present in omap_hsmmc driver). When sdhci-omap driver is modified to disable regulator during shutdown, something like device_link_add() can be added in _regulator_get(). Since this doesn't reintroduce the problem that was solved by 52cdbdd49853, this can be safely merged. Reviewed-by: Kishon Vijay Abraham I <kishon@xxxxxx> Thanks Kishon
