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

From: Tony Lindgren <tony@atomide.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Haojian Zhuang <haojian.zhuang@linaro.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Nishanth Menon <nm@ti.com>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linux-OMAP <linux-omap@vger.kernel.org>
Subject: Re: [PATCH 1/5] pinctrl: core: Use delayed work for hogs
Date: Fri, 2 Dec 2016 08:44:06 -0800	[thread overview]
Message-ID: <20161202164406.GA4705@atomide.com> (raw)
In-Reply-To: <CACRpkdZUtqEUQbz7YqtLnYWdOmW4g4q4ikRuqfCwzf5kMR5JDg@mail.gmail.com>

* Linus Walleij <linus.walleij@linaro.org> [161202 05:08]:
> On Tue, Nov 15, 2016 at 6:08 PM, Tony Lindgren <tony@atomide.com> wrote:
> > * Tony Lindgren <tony@atomide.com> [161115 07:42]:
> >> * Linus Walleij <linus.walleij@linaro.org> [161114 22:53]:
> >> > On Tue, Nov 15, 2016 at 1:47 AM, Tony Lindgren <tony@atomide.com> wrote:
> >> >
> >> > > 8< --------------------------------
> >> > > From tony Mon Sep 17 00:00:00 2001
> >> > > From: Tony Lindgren <tony@atomide.com>
> >> > > 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@atomide.com>
> >> >
> >> > 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?
> 
> Sorry for the lack of attention to this patch set on my part. :(
> 
> Do you think you could resend these last 5 patches after the
> release of v4.10-rc1 so we merge it early for the next cycle
> and people get a chance to test and see if it works well for
> everyone?

Yeah no problem, too late to do anything with them right now :)

> I'm worried about adding it to the tree this late in the kernel
> cycle...

Yup me too.

> However I like the look of the series overall a lot.

OK good to hear.

Tony