[lkml]   [2017]   [Dec]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Linux 4.15-rc2: Regression in resume from ACPI S3
So I was finally able to figure out what the hell is going on:


- The device suspend code puts the graphics card into a power
state != PCI_D0.

- Offline non boot CPUs

- Break interrupt affinity. Allocate new vector on CPU 0, compose and
write MSI message which ends up in:

__pci_write_msi_msg(entry, msg)
if (dev->current_state != PCI_D0 || pci_dev_is_disconnected(dev)) {
/* Don't touch the hardware now */
} else {
entry->msg = *msg;

So because the device is not in PCI_D0 the message is not written. It's
written in the device resume path.

[ 139.670446] ACPI: Low-level resume complete
[ 139.670541] PM: Restoring platform NVS memory
[ 139.672462] do_IRQ: 0.55 No irq handler for vector
[ 139.672475] Enabling non-boot CPUs ...

So the spurious interrupt happens early and way before the device resume
code writes the new MSI message.

I checked the behaviour on 4.14. The MSI write is delayed there in the same
way, but there is no spurious interrupt. There is no interrupt coming in at
all _BEFORE_ the device is put out of PCI_D0.

And this has certainly nothing to do with the vector management changes,
but I can't figure yet what makes that spurious interrupt to be sent.

Any ideas welcome.



 \ /
  Last update: 2017-12-13 16:58    [W:0.101 / U:3.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site