linux-kernel - Re: [PATCH 4/6] pinctrl: single: Add support for wake-up interrupts

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Date:	Fri, 11 Oct 2013 10:00:35 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Roger Quadros <rogerq@...com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	Prakash Manjunathappa <prakash.pm@...com>,
	Haojian Zhuang <haojian.zhuang@...aro.org>,
	Benoît Cousson <bcousson@...libre.com>,
	Linux-OMAP <linux-omap@...r.kernel.org>
Subject: Re: [PATCH 4/6] pinctrl: single: Add support for wake-up interrupts

On Thu, Oct 10, 2013 at 6:20 PM, Tony Lindgren <tony@...mide.com> wrote:
> * Linus Walleij <linus.walleij@...aro.org> [131010 09:19]:
>> On Thu, Oct 10, 2013 at 6:00 PM, Tony Lindgren <tony@...mide.com> wrote:
>> > * Roger Quadros <rogerq@...com> [131010 06:32]:
>> >>
>> >> I tried testing this with the USB EHCI driver, but I'm not getting wake up interrupts
>> >> while the system is still running and only the EHCI controller is runtime suspended.
>> >>
>> >> It seems we need to somehow call _reconfigure_io_chain() to update the daisy chain
>> >> whenever the pad wakeup_enable bit is changed.
>> >
>> > Sounds like this is on omap3? Have you tried calling pcs_soc->rearm() in the
>> > pcs_irq_handle() like the comments there suggest? At least for me that keeps
>> > the wake-up interrupts continuously running on omap3 instead of just idle modes.
>>
>> If the rearm() function is calling this _reconfigure_io_chain my comments
>> on the fact that this is something that should be handled by the pin
>> control driver still apply I think ....
>
> Yes, except that the reconfigure_io_chain registers are in the PRM module, not in
> the SCM module where the pinctrl registers are.. And that shared PRM interrupt is
> used mostly for the internal domain wake-ups, so we should keep that in the PRM
> driver.

That depends.

One-iorange-equals-one-driver is a fallacy, especially given that MFD for
memory-mapped things exist for a reason.

What the pin control driver should do is control the pins. Whether the registers
are spread out in the entire IO-memory does not matter. We did have one system
which placed the IO-muxing together with each peripheral (!) and I did
still want
that to be handled by a single pinctrl driver picking out windows to all these
IO-ranges.

Things like the PRM which has (my guess) a gazillion registers related to its
deep-core SoC stuff should be handled by things like
drivers/mfd/syscon.c, which means it is dead simple for some other driver
using "just this one register" in that range to get a handle at it and poke it
using syscon_node_to_regmap() (just derference an ampersand ref)
syscon_regmap_lookup_by_compatible() (use a compatible string)
all returning a regmap * that you can use to poke these registers.

Yours,
Linus Walleij
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