Comment by halz | Hacker News Reader

Comment by halz | Hacker News Reader

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Yes, ACPI DSDT being utterly broken seems to be a pretty common trip point for Linux suspend/sleep. For my Dell Precision 5510, I was able to patch[1] a missing device back into the DSDT, as well as 'fix' some thunderbolt port enumeration race condition. The hackintosh community was helpful in providing ACPI dumps from similar enough Dell systems in the same generation that I was able to paste in the missing device to get very consistent S3 performance. Using `acpiexec` was very helpful to simulate invoking sleep/suspend and being able to follow the execution path of where it would get stuck.

Also want to add that random wakeups can be triggered by interrupts hitting devices in `/proc/acpi/wakeup`. These wakeup sources can be selectively disabled once the problematic ones are identified. I disable XHC (USB ports), because it seems my routine closes the lid to suspend and _then_ remove peripherals.. which can cause a wakeup!

[1] https://gist.github.com/mailhost/d5b27b247fa26d8bdc8a5d20223...

> The hackintosh community was helpful in providing ACPI dumps from similar enough Dell systems in the same generation that I was able to paste in the missing device to get very consistent S3 performance.

+1. I love the Hackintosh community. Hackintosh forums are a gold mine of solutions to all types of ACPI DSDT problems. Many great tutorials, really helpful to Linux users. If the Hackintosh community doesn't exist, it wouldn't be possible. Not only DSDT, their EFI resources are also great, probably the biggest PC userbase of EFI bootloaders - earlier in this year I used a Hackintosh EFI device driver from Clover (free and open source) to help me booting from NVMe without BIOS support. In my previous life I also solved a non-standard graphics problem by backporting Hackintosh solution to Linux. Looking back, trying Hackintosh turned out to be a great decision, despite I only used it for a few months before quitting (I decided that voluntarily lock myself in a walled garden, then spent a lot of time installing a free software working environment back is unwise), otherwise I could not know its community and innovations.

> Using `acpiexec` was very helpful to simulate invoking sleep/suspend and being able to follow the execution path of where it would get stuck. Also want to add that random wakeups can be triggered by interrupts hitting devices in `/proc/acpi/wakeup`. These wakeup sources can be selectively disabled once the problematic ones are identified. I disable XHC (USB ports)

Thanks for the tip. I hope I'll never have to use it, but it could definitely help if I had to use yet another broken laptop for some reasons.

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