Re: [PATCH 1/5] pinctrl: core: Use delayed work for hogs

[Tony Lindgren]

* Tony Lindgren <tony@xxxxxxxxxxx> [161115 07:42]:
> * Linus Walleij <linus.walleij@xxxxxxxxxx> [161114 22:53]:
> > On Tue, Nov 15, 2016 at 1:47 AM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> > 
> > > 8< --------------------------------
> > > From tony Mon Sep 17 00:00:00 2001
> > > From: Tony Lindgren <tony@xxxxxxxxxxx>
> > > Date: Tue, 25 Oct 2016 08:33:35 -0700
> > > Subject: [PATCH] pinctrl: core: Use delayed work for hogs
> > >
> > > Having the pin control framework call pin controller functions
> > > before it's probe has finished is not nice as the pin controller
> > > device driver does not yet have struct pinctrl_dev handle.
> > >
> > > Let's fix this issue by adding deferred work for late init. This is
> > > needed to be able to add pinctrl generic helper functions that expect
> > > to know struct pinctrl_dev handle. Note that we now need to call
> > > create_pinctrl() directly as we don't want to add the pin controller
> > > to the list of controllers until the hogs are claimed. We also need
> > > to pass the pinctrl_dev to the device tree parser functions as they
> > > otherwise won't find the right controller at this point.
> > >
> > > Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> > 
> > This looks a lot better!
> > 
> > So if I understand correctly, we can guarantee that the delayed
> > work will not execute until the device driver probe() has finished,
> > and it *will* execute immediately after that?
> > 
> > So:
> > - Device driver probes
> > - Delayed work is called
> > - Next initcall
> > 
> > I'm not 100% familiar with how delayed work works... :/
> 
> Yeah well the delayed work gets scheduled for next jiffy but may
> be pre-empted as it runs in process context.
> 
> So in the worst case it could that we still may need to fix few
> drivers to support -EPROBE_DEFER. I wonder if we should check for
> hogs in probe already and only defer if hogs are defined?

Below is a version using delayed_work only if pinctrl_dt_has_hogs().

Not sure if testing only for pinctrl-0 is enough there though?

Regards,

Tony

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