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

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Date:	Fri, 11 Oct 2013 11:56:30 +0300
From:	Roger Quadros <rogerq@...com>
To:	Linus Walleij <linus.walleij@...aro.org>
CC:	Tony Lindgren <tony@...mide.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 10/11/2013 11:00 AM, Linus Walleij wrote:
> 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.

+1

Another place I faced a similar problem was the OMAP control module, which contains
registers for a number of different non related peripherals. (e.g. PHY for USB, SATA,
Display clock, etc)

> 
> 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.

The register handling is fine. But how do we deal with resource handling?
e.g. the block that has the deep-core registers might need to be clocked or powered
before the registers can be accessed.

cheers,
-roger
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