Re: [PATCH] [RFC] PCI/PM: Do not RPM suspend devices without drivers

[Marek Vasut <marex@denx.de>]

On 10/13/24 1:03 PM, Lukas Wunner wrote:
> On Sat, Oct 12, 2024 at 02:48:48AM +0200, Marek Vasut wrote:
>> The pci_host_probe() does reallocate BARs for devices which start up with
>> uninitialized BAR addresses set to 0 by calling pci_bus_assign_resources(),
>> which updates the device config space content.
>>
>> At the same time, pci_pm_runtime_suspend() triggers pci_save_state() for
>> all devices which do not have drivers assigned to them to store current
>> content of their config space registers.
> [...]
>> Work around the issue by not suspending pci_bus_type devices which do
>> not have driver assigned to them, keep those devices active to prevent
>> pci_save_state() from being called. Once a proper driver takes over, it
>> can RPM manage the device correctly.
> 
> It sounds like you may want to acquire a runtime PM reference
> or disable runtime PM for the duration of the bus scan (or at
> least device scan) rather than the proposed workaround.
I was hoping to get at least an confirmation that this issue really 
exists and that I'm not chasing some nonsense. Thoughts ?