Bug#964839: bbswitch-dkms: Fails to re-enable graphics after suspend with kernel 5.7

[Felix Dörre]

Thanks for the hint, this are the observations:
On 5.6:

[389399.743191] PM: suspend entry (deep)
[389399.766750] Filesystems sync: 0.023 seconds
[389399.767062] (NULL device *): firmware: direct-loading firmware 
i915/kbl_dmc_ver1_04.bin
[389399.767088] (NULL device *): firmware: direct-loading firmware 
intel/ibt-12-16.ddc
[389399.767167] (NULL device *): firmware: direct-loading firmware 
regulatory.db
[389399.767170] (NULL device *): firmware: direct-loading firmware 
regulatory.db.p7s
[389399.768870] (NULL device *): firmware: direct-loading firmware 
intel/ibt-12-16.sfi
[389399.770169] (NULL device *): firmware: direct-loading firmware 
iwlwifi-8265-36.ucode
[389399.770188] bbswitch: bbswitch_pm_handler: event_type=3 
is_card_disabled=1 dis_before_suspend_disabled=0
[389399.770189] bbswitch: enabling discrete graphics
[389399.920138] Freezing user space processes ... (elapsed 0.004 
seconds) done.
[389399.924632] OOM killer disabled.
[389399.924633] Freezing remaining freezable tasks ... (elapsed 0.001 
seconds) done.
[389399.926456] printk: Suspending console(s) (use no_console_suspend to 
debug)
....
[389408.348659] OOM killer enabled.
[389408.348660] Restarting tasks ... done.
[389408.428103] bbswitch: bbswitch_pm_handler: event_type=4 
is_card_disabled=0 dis_before_suspend_disabled=1
[389408.428106] bbswitch: disabling discrete graphics
[389408.493000] pci 0000:01:00.0: refused to change power state from D0 
to D3hot
[389408.495182] PM: suspend exit

On 5.7:
[   89.560733] PM: suspend entry (deep)
[   89.656060] Filesystems sync: 0.095 seconds
[   89.656623] (NULL device *): firmware: direct-loading firmware 
regulatory.db
[   89.656630] (NULL device *): firmware: direct-loading firmware 
regulatory.db.p7s
[   89.657274] (NULL device *): firmware: direct-loading firmware 
iwlwifi-8265-36.ucode
[   89.657646] (NULL device *): firmware: direct-loading firmware 
i915/kbl_dmc_ver1_04.bin
[   89.777521] Freezing user space processes ... (elapsed 0.003 seconds) 
done.
[   89.780568] OOM killer disabled.
[   89.780569] Freezing remaining freezable tasks ... (elapsed 0.001 
seconds) done.
[   89.782023] printk: Suspending console(s) (use no_console_suspend to 
debug)
....
[   93.238967] OOM killer enabled.
[   93.238968] Restarting tasks ... done.
[   93.304163] bbswitch: bbswitch_pm_handler: event_type=4 
is_card_disabled=1 dis_before_suspend_disabled=0
[   93.304165] PM: suspend exit

So to me, it seems that the suspend event is just missing.

Another, independent experiment has shown, that this missing 
reactivation is the cause for the problem: Enabling the card manually 
before going to suspend is a workaround for the problem.

Kind regards,
Felix