Created attachment 300347 [details]
Dell XPS 9550 (2015)
On 5.15 and 5.16 kernels, if my laptop is plugged in prior to booting or is plugged in at any time after booting I see high CPU usage (80-100% of a core) by IRQ 16, with a constant 15k+ IRQ events per second, whether the system is in use or not. Unplugging the laptop does not make the events stop. If I boot the system without it being plugged in the issue does not occur until I plug it in. Downgrading to 5.14 fixes the issue completely, with only 3 total IRQ 16 interrupts after the system as been running for > 20 minutes. I do not see IRQ16 interrupts increase by using the touch pad, keyboard, or touch screen. I believe I was able to bisect the introduction of the issue to commit 357cf0cdddceea974a7d32668a0df0d9f77055cb, but this was the first time I've done kernel bisects before, so I may be incorrect. I tested with 5.17 RC1 and the issue was still present.
I've attached dmesg output and the contents of lspci -vvvv, as well as included IRQ 16 info from /proc/interrupts. Please let me know if I can provide anything else.
16: 0 0 7513443 0 0 0 0 0 IR-IO-APIC 16-fasteoi idma64.0, i801_smbus, i2c_designware.0
Created attachment 300348 [details]
I think I was incorrect when I said it was in kernel 5.15, when I was bisecting to find the issue the Makefile release information said 5.15-rc2 so I assumed it was in 5.15, but that looks like I was incorrect. I'll test on 5.15 and verify whether it is present there.
I've confirmed that I do not see the issue on kernel 5.15, only on 5.16.
Duplicate of https://bugzilla.kernel.org/show_bug.cgi?id=215533.
Thanks for adding your observations on the IRQ events though.
Agreed, marked as duplicate.
*** This bug has been marked as a duplicate of bug 215533 ***