Hi, On Tue, Jul 10, 2018 at 2:22 PM, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: > 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. This is very useful information, let me add it to the patch changelog. > Reviewed-by: Kishon Vijay Abraham I <kishon@xxxxxx> Thank you!
