On Wed, Dec 18, 2019 at 11:34:58AM +0000, Mark Brown wrote: > On Tue, Dec 17, 2019 at 11:51:55PM +0800, Siddharth Kapoor wrote: > > > I would like to share a concern with the regulator patch which is part of > > 4.9.196 LTS kernel. > > That's an *extremely* old kernel. It is, but it's the latest stable kernel (well close to), and your patch was tagged by you to be backported to here, so if there's a problem with a stable branch, I want to know about it as I don't want to see regressions happen in it. > > https://lore.kernel.org/lkml/20190904124250.25844-1-broonie@xxxxxxxxxx/ > > That's the patch "[PATCH] regulator: Defer init completion for a while > after late_initcall" which defers disabling of idle regulators for a > while. > > Please include human readable descriptions of things like commits and > issues being discussed in e-mail in your mails, this makes them much > easier for humans to read especially when they have no internet access. > I do frequently catch up on my mail on flights or while otherwise > travelling so this is even more pressing for me than just being about > making things a bit easier to read. > > > We have reverted the patch in Pixel kernels and would like you to look into > > this and consider reverting it upstream as well. > > I've got nothing to do with the stable kernels so there's nothing I can > do here, sorry. Should I revert it everywhere? This patch reads as it should be fixing problems, not causing them :) > However if this is triggering anything it's almost > certainly some kind of timing issue (this code isn't new, it's just > being run a bit later) and is only currently working through luck so I > do strongly recommend trying to figure out the actual problem since it's > liable to come back and bite you later - we did find one buggy driver in > mainline as a result of this change, it's possible you've got another > one. > > Possibly your GPU supplies need to be flagged as always on, possibly > your GPU driver is forgetting to enable some supplies it needs, or > possibly there's a missing always-on constraint on one of the regulators > depending on how the driver expects this to work (if it's a proprietary > driver it shouldn't be using the regulator API itself). I'm quite > surprised you've not seen any issue before given that the supplies would > still be being disabled earlier. Timing "luck" is probably something we shouldn't be messing with in stable kernels. How about I revert this for the 4.14 and older releases and let new devices deal with the timing issues when they are brought up on new hardware? thanks, greg k-h
