[Bug 57201] New: [vgaswitcheroo] increased consumption and hangups after hibernating with disabled radeon

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=57201

           Summary: [vgaswitcheroo] increased consumption and hangups
                    after hibernating with disabled radeon
           Product: Drivers
           Version: 2.5
    Kernel Version: 3.9-rc8-24-gd7d7271
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Video(DRI - non Intel)
        AssignedTo: drivers_video-dri at kernel-bugs.osdl.org
        ReportedBy: nikoamia at gmail.com
                CC: nikoamia at gmail.com
        Regression: No


Created an attachment (id=100101)
 --> (https://bugzilla.kernel.org/attachment.cgi?id=100101)
lspci -vv (from the older kernel)

After hibernation with disabled radeon and resuming, vgaswitcheroo thinks that
discrete card is powered down, but in fact it is not. It consumes power, and
attemts to disable it again hangups the system.

Steps to reproduce:
1. Start system, switch to intel (if needed), disable unused card (echo DDIS
and OFF to /sys/kernel/debug/vgaswitcheroo/switch)
2. Check power consumption (for example, with powertop)
3. Hibernate the system, resume
4. Check power consumption again, notice increase

If attempting to re-disable card (echo ON and OFF) echo hang-ups after ON. If
you SIGINT echo, whole system will hangup.

On the older 3.8.8 kernel the behaviour is somewhat different:
1. Echo ON and OFF, the power consumption will go down.
2. Hibernate the system again, resume.
3. Notice power consumption increase again.
4. Echo ON.
And system hangups just like with newer kernel.

A workaround is to enable card before hibernation and disable it after resuming
--- it works in both kernels.

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