Re: [PATCH] PM / runtime: Fixup reference counting of device link suppliers at probe

[Ulf Hansson]

On 18 May 2018 at 10:58, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
> On Fri, May 18, 2018 at 10:48 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>> In the driver core, before it invokes really_probe() it runtime resumes the
>> suppliers for the device via calling pm_runtime_get_suppliers(), which also
>> increases the runtime PM usage count for each of the available supplier.
>>
>> This makes sense, as to be able to allow the consumer device to be probed
>> by its driver. However, if the driver decides to add a new supplier link
>> during ->probe(), hence updating the list of suppliers,
>
> Do any of the existing drivers do that?

Yes.

At least these, but possibly even more...

drivers/gpu/drm/rockchip/rockchip_drm_drv.c
drivers/gpu/drm/tegra/dc.c
drivers/gpu/ipu-v3/ipu-prg.c
drivers/pci/dwc/pci-dra7xx.c

>
>> the following call to pm_runtime_put_suppliers(), invoked after really_probe()
>> in the driver core, we get into trouble.

Kind regards
Uffe