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The Qualcomm msm8909w SoC doesn't enter suspend mode
Join Date: 12 Oct 20
Posts: 1
Posted: Mon, 2020-10-12 08:09
The Qualcomm msm8909w SoC doesn't enter suspend mode
I'm trying to get my Qualcomm msm8909w SoC [1] to enter sleep (to ram) state but I fail, need your advice on why it would fail / wakeup continuously.
No matter how hard I try it either:
* Keeps waking up shortly after it goes to suspend mode
(suspend_ops->enter(state)), or
* It doesn't enter sleep mode at all.
This is what you see from ftrace:
              sh-2073  [001] d..1 23035.549297: suspend_resume:
machine_suspend[3] begin
              sh-2073  [001] d..1 23035.549297: suspend_resume:
machine_suspend[3] end
Notice no diff in the timestamp, the suspend_ops->enter should have
blocked indefinitely until the next real interrupt arrives (e.g.
keyboard event / network event / power button press).
It's hard to tell the reason why, really. The only thing I have is the
ftrace traces (more on that at the bottom of the thread).
Since you won't find a call to WFI ARM instruction to sleep, and the
sleep is managed by Qualcomm's proprietary closed firmware blob, I
could really use some advice here from ARM / QCOM people on tracing
the culprit that keeps the SoC awake.


Call stack
#-1 arm_proprietary_secure_firmware()
    Here we are in the "ARM Secure Zone" with a proprietary closed firmware blob
    that is supposed to drive the core to a deep sleep.
    I'm guessing that under the hood it should call:
    wfi // for each core sleep mode
#0 scm_call_atomic1 (scm.c), (called with SCM_SVC_BOOT,
#1 msm_pm_collapse (msm-pm.c)
#2 __cpu_suspend_enter (sleep.S)
#3 __cpu_suspend (suspend.c)
#4 msm_pm_spm_power_collapse (msm-pm.c)
#5 msm_pm_power_collapse (msm-pm.c), (called with mode ==
#6 msm_cpu_pm_enter_sleep (msm-pm.c)
#7 lpm_suspend_enter (lpm-levels.c)
#8 suspend_enter (suspend.c) (called with PM_SUSPEND_MEM)
Appreciate your input.
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