Re: [REGRESSION][BISECTED] Dell Precision 7780 wakes up on its own from suspend

Mario Limonciello
2025-06-27T00:35:12Z

On 6/26/25 6:32 PM, Askar Safin wrote:
> Hi. This commit:
>
> #regzbot introduced: 1796f808e4bb2c074824dc32258ed1e719370cb3
>
> caused a regression. Dell Precision 7780 often wakes up on its own from suspend.
> Sometimes wake up happens immediately (i. e. within 7 seconds), sometimes it happens after, say, 30 minutes.
>
> (The laptop comes with Ubuntu preinstalled, but I didn't test this bug on preinstalled Ubuntu)
>
> That commit already caused a lot of other regressions on other laptops:
>
> #regzbot link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4cb786180dfb5258ff3111181b5e4ecb1d4a297b
> #regzbot link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d63f11c02b8d3e54bdb65d8c309f73b7f474aec4
> #regzbot link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a69982c37cd0586e6832268155349301b87f2e35
> #regzbot link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=782eea0c89f7d071d6b56ecfa1b8b0c81164b9be
>
> I will be available for testing in coming days, then I will switch to other things, and so will not be available for testing.
> If you want more time, then, please, ask for it, i. e. say me something like "Please, be available for testing in more 10 days".
>
> Here is config I used for testing:
>
> https://zerobin.net/?5c4e4b8f6e7a6a0d#W35/IXYAxzjFyp7yP71V0EZ6jcF83HOWB/52ldl5jig=
>
> In other words, this is config I used for bisecting. In other words, the bug reproduces
> with this config on 1796f808, but doesn't reproduce on d86388c9.
>
> This config was created using localmodconfig, so it is quite possible it will not boot on other computers.
>
> Also, the bug reproduces on pretty standard Debian kernels, for example, on
>
> http://deb.debian.org/debian/pool/main/l/linux-signed-amd64/linux-image-6.12.32-amd64_6.12.32-1_amd64.deb
>
> with standard Debian config.
>
> Here is "bad" dmesg:
> https://zerobin.net/?525f36df8d698fba#e3+DHsvv3Lsqmi91d1TqHx19mrilYNDR0bL8DbeNxw0=
>
> I. e. this is dmesg generated during attempts to reproduce the bug on "bad" kernel, i. e. on 1796f808
> with minimized config provided above.
>
> And here is "good" dmesg:
> https://zerobin.net/?09b26bfcfa523eff#zDMKsIGmfXBLgpml3qDjwW0NnclErstolYEjCMzmmsA=
>
> I. e. it was generated the same way, but with d86388c9.
>
> This is script I used for bisecting:
>
> https://zerobin.net/?a2acfc92e5a33cc3#L7/Z0jY47FFFp7UJ1GPmbhmfrcMTr0zBZst82ubyDs8=
>
> The script uses "rtcwake" to automatize bisecting. Note that the bug reproduces
> not only with "rtcwake", but also with normal suspend initiated from GUI without any timer.
>
> This bug causes "rtcwake" to wake up BEFORE specified time.
>
> Bug sometimes reproduces and sometimes not, so script above makes multiple attempts.
>
> The script writes some info to /dev/kmsg , and you may see its output in dmesg above.
>
> If you need more info, ask me. But again: I will be available within some days and then not.
> If you need more time, ask me for it.
>
> Reverting commit 1796f808 on top of v6.12.32 causes the bug to disappear.
>
> When I connect external wireless mouse via USB, then the bug becomes harder to reproduce,
> so I did testing without anything connected to laptop (except for power source).
>
> --
> Askar Safin
> https://types.pl/@safinaskar
>
>

In order to debug this a few helpful things to add to your script:
1) Set /sys/power/pm_debug_messages before starting
2) Capture the value of /sys/power/suspend_stats/last_hw_sleep

BTW - When a wireless mouse is connected via USB I /suspect/ you aren't
getting into hardware sleep state (or if your it's for not as long of a
duration). I'm not sure if that's a hint for this issue or not right
now. That's why I think capturing it might be helpful for this issue.