Hi Rafael, "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> wrote on Thu, 13 Dec 2018 22:50:51 +0100: > On Thursday, December 13, 2018 3:30:00 PM CET Miquel Raynal wrote: > > Hi Lorenzo, > > > > > > If that's really the case, then I can see how one device and it's > > > > children are suspended and the irq for it is disabled but the providing > > > > devices (clk, regulator, bus controller, etc.) are still fully active > > > > and not suspended but in fact completely usable and able to service > > > > interrupts. If that all makes sense, then I would answer the question > > > > with a definitive "yes it's all fine" because the clk consumer could be > > > > in the NOIRQ phase of its suspend but the clk provider wouldn't have > > > > even started suspending yet when clk_disable_unprepare() is called. > > > > > > That's a very good summary and address my concern, I still question this > > > patch correctness (and many others that carry out clk operations in S2R > > > NOIRQ phase), they may work but do not tell me they are rock solid given > > > your accurate summary above. > > > > I understand your concern but I don't see any alternative right now > > and a deep rework of the PM core to respect such dependency is not > > something that can be done in a reasonable amount of time. > > Maybe you don't need to rework anything. :-) > > Have you considered using device links? Absolutely, yes :) I am actively working on it in parallel, you can check the third version there [1]. Stephen Boyd has a slightly different idea of how it should be done, I will propose a v4 this week, I can add you in copy if you are interested! Anyway, there is one thing that is still missing: * Let's have device A that requests clock B * With the device link series, A is linked (as a child) to B. * A suspend/resume hooks handle things in the NOIRQ phase. * B suspend/resume hooks handle things in the default phase. What I expected during a suspend: 1/ ->suspend_noirq(device A) 2/ ->suspend(clock B) Unfortunately, device links do not seem to enforce any priority between phases (default/late/noirq) and what happens is: 1/ ->suspend(B) 2/ ->suspend_noirq(A) Which has no sense in my case. Hence, I had to request the clock suspend/resume callbacks to be upgraded to the NOIRQ phase as well (I don't have a better solution for now). This is still under discussion in a thread you have been recently added to by Bjorn, see [2]. So when I told you I was not confident in "reworking the PM core to respect such dependency", this is what I was referring to. I am definitely ready to help, but I don't feel I can do it alone. [1] https://www.spinics.net/lists/linux-clk/msg32824.html [2] https://marc.info/?l=linux-pm&m=154465198510735&w=2 Thanks, Miquèl
