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

[Felix Dörre]

On 2020-07-31 10:50, Andreas Beckmann wrote:
> I'd guess that bbswitch needs to be adusted to the corresponding kernel
> changes.

I just compared the log output to the bbswitch source code and from what 
I can tell:

- There is logic to always enable the discrete graphics card just before 
standby:
 > enable the device before suspend to avoid the PCI config space from 
being saved incorrectly
- This logic does not seem to be invoked:
from 5.6:
[   37.338585] Filesystems sync: 3.833 seconds
[   37.339219] (NULL device *): firmware: direct-loading firmware 
regulatory.db
[   37.339222] (NULL device *): firmware: direct-loading firmware 
regulatory.db.p7s
[   37.339918] (NULL device *): firmware: direct-loading firmware 
iwlwifi-8265-36.ucode
[   37.340208] (NULL device *): firmware: direct-loading firmware 
i915/kbl_dmc_ver1_04.bin
[   37.340311] bbswitch: enabling discrete graphics
[   37.493527] Freezing user space processes ... (elapsed 0.003 seconds) 
done.
[   37.496725] OOM killer disabled.
[   37.496727] Freezing remaining freezable tasks ... (elapsed 0.001 
seconds) done.
from 5.7:
[   42.399698] Filesystems sync: 2.100 seconds
[   42.400331] (NULL device *): firmware: direct-loading firmware 
regulatory.db.p7s
[   42.400338] (NULL device *): firmware: direct-loading firmware 
regulatory.db
[   42.401065] (NULL device *): firmware: direct-loading firmware 
iwlwifi-8265-36.ucode
[   42.401339] (NULL device *): firmware: direct-loading firmware 
i915/kbl_dmc_ver1_04.bin
[   42.523291] Freezing user space processes ... (elapsed 0.003 seconds) 
done.
[   42.526435] OOM killer disabled.
[   42.526436] Freezing remaining freezable tasks ... (elapsed 0.001 
seconds) done.

The next step would probably be to look if this 
"register_pm_notifier(&nb)" is intended to not work and there is a 
replacement, or what is happening there.

-- 
Kind regards,
Felix Dörre