On Tue, Nov 26, 2024 at 9:37 PM Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx> wrote: > > On Tue, Nov 26, 2024 at 04:00:42PM +0800, Hsin-Te Yuan wrote: > > On Tue, Nov 26, 2024 at 5:21 AM Nícolas F. R. A. Prado > > <nfraprado@xxxxxxxxxxxxx> wrote: > > > > > > When configured in filtered mode, the LVTS thermal controller will > > > monitor the temperature from the sensors and trigger an interrupt once a > > > thermal threshold is crossed. > > > > > > Currently this is true even during suspend and resume. The problem with > > > that is that when enabling the internal clock of the LVTS controller in > > > lvts_ctrl_set_enable() during resume, the temperature reading can glitch > > > and appear much higher than the real one, resulting in a spurious > > > interrupt getting generated. > > > > > This sounds weird to me. On my end, the symptom is that the device > > sometimes cannot suspend. > > To be more precise, `echo mem > /sys/power/state` returns almost > > immediately. I think the irq is more > > likely to be triggered during suspension. > > Hi Hsin-Te, > > please also check the first paragraph of the cover letter, and patch 2, that > should clarify it. But anyway, I can explain it here too: > > The issue you observed is caused by two things combined: > * When returning from resume with filtered mode enabled, the sensor temperature > reading can glitch, appearing much higher. (fixed by this patch) > * Since the Stage 3 threshold is enabled and configured to take the maximum > reading from the sensors, it will be triggered by that glitch and bring the > system into a state where it can no longer suspend, it will just resume right > away. (fixed by patch 2) > > So currently, every so often, during resume both these things will happen, and > any future suspend will resume right away. That's why this was never observed by > me when testing a single suspend/resume. It only breaks on resume, and only > affects future suspends, so you need to test multiple suspend/resumes on the > same run to observe this issue. > > And also since both things are needed to cause this issue, if you apply only > patch 1 or only patch 2, it will already fix the issue. > > Hope this clarifies it. > > Thanks, > Nícolas Thanks for the explanation! Regards, Hsin-Te
