[PATCH] pmdomain: imx: gpc: set fwnode from parent device

[Ulf Hansson]

On Tue, 17 Oct 2023 at 10:00, Emil Kronborg Andersen <emkan at prevas.dk> wrote:
>
> Hi Ulf,
>
> On Mon, Oct 16, 2023 at 11:53 +0200, Ulf Hansson wrote:
> > Unfortunately, it's not that easy. It's not required by
> > pm_genpd_init() (or of_genpd_add_provider_*) to use a struct *device
> > when registering a genpd provider. In fact, that's also the reason why
> > pm_genpd_init() needs to initialize its own struct device.
>
> Do you see any way to do it properly at pmdomain level instead, or is
> that not feasible? I agree with Saravana that a centralized solution,
> akin to what was implemented for tty devices in commit 1a5ecc73b2bf
> ("serdev: Set fwnode for serdev devices"), would be ideal. However, I
> was not able to find other reports or patches of problems regarding
> fw_devlink at pmdomain level, so it might not be a general problem here,
> and fixes per driver might be okay in this case?

Sure, we could fix it though a centralized solution, but it requires
us to patch each and every genpd provider driver too. At this point I
would therefore say, let's just fix it for those that need it.

>
> > That said, can you please explain the special condition that caused
> > this thing to be needed in the first place?
>
> I noticed this issue when I updated from 5.15.93 to 6.1.37. Except for
> the commit I bisected, i.e., 3fb16866b51d ("driver core: fw_devlink:
> Make cycle detection more robust"), I found that the issue was
> introduced somewhere between 6.1.16 and 6.1.15. Here, some commits
> regarding fw_devlink was backported, which might be relevant:
>
> $ git log --oneline v6.1.15..v6.1.16 -- drivers/base/core.c | grep fw_devlink
> 11d93294b7c3 driver core: fw_devlink: Avoid spurious error message
> 3dd596616d10 driver core: fw_devlink: Make cycle detection more robust
> a3c171751512 driver core: fw_devlink: Improve check for fwnode with no device/driver
> 7a8ce4d2fbbc driver core: fw_devlink: Consolidate device link flag computation
> 16aa2487cf15 driver core: fw_devlink: Allow marking a fwnode link as being part of a cycle
> eaf9b5612a47 driver core: fw_devlink: Don't purge child fwnode's consumer links
> 2455b81afe68 driver core: fw_devlink: Add DL_FLAG_CYCLE support to device links

Thanks for sharing the commits. I haven't looked much closer to them,
but maybe Saravana has some ideas about whether this potentially can
be fixed in the fw_devlink parsing instead?

Kind regards
Uffe