From: Lee Jones <lee.jones@linaro.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Grant Likely <grant.likely@secretlab.ca>,
sameo@linux.intel.com, devicetree-discuss@lists.ozlabs.org,
spear-devel@list.st.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 3/3] mfd: stmpe: Update DT support in stmpe driver
Date: Mon, 26 Nov 2012 11:18:45 +0000 [thread overview]
Message-ID: <20121126111845.GG12782@gmail.com> (raw)
In-Reply-To: <CAKohpomAM2pw9kgB6khtHzQ2WCXKZ9_pi1_sOH2dQToVS8ep4w@mail.gmail.com>
On Fri, 23 Nov 2012, Viresh Kumar wrote:
> On 23 November 2012 15:11, Grant Likely <grant.likely@secretlab.ca> wrote:
> > On Fri, 23 Nov 2012 00:26:20 +0530, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> >> + - irq-trigger : IRQ trigger to use for the interrupt to the host
> >> + - irq-invert-polarity : bool, IRQ line is connected with reversed polarity
> >
> > This looks odd. Normally the interrupt polarity should be encoded in the irq
> > specifier flags field.
>
> Hi Grant and Lee Jones,
>
> This looks odd because stmpe is odd, i am taking the discussion held
> with Lee jones to this thread.
STMPE isn't odd or special in any way. :)
> So, how interrupt stuff works currently in DT..
> We have a interrupt controller IC:
>
> ic: interrupt-controller@40008000 {
> compatible = "foo";
> interrupt-controller;
> #interrupt-cells = <2>;
> ...
> };
>
> And we have a user of this IC:
>
> foo-peripheral@40048000 {
> compatible = "foo-peripheral";
> interrupt-parent = <&ic>;
> interrupts = <39 4>;
> };
>
> Here first field of "interrupts" gives interrupt line number and the second one
> gives polarity, interrupt type etc..
So far so good.
> All is good till now. Now, every interrupt controller supports the first
> field, but the second one depends on its capabilities. An interrupt controller
> might not have registers to configure interrupt polarity, type, etc of
> the interrupt
> it will service and so the second field wouldn't be available for them.
>
> For now just think stmpe is not a MFD and not a interrupt controller
> either. It is
> just a simple device, dev-foo.
>
> It will declare values of its interrupts field based on the type of
> interrupt controller
> that will service its interrupt and that can be anything like VIC/GIC/GPIO
> controller.
>
> Obviously nobody else than the parent IC driver can parse interrupts field
> of dev-foo, because only that driver understands the real meaning of
> these fields.
>
> Now, stmpe has a special property. It can decide the way its output
> interrupt line
> will work. i.e. its polarity and interrupt type - edle/level, etc..
> This is not commonly
> seen in any peripheral. Now my original bindings and the real question here is
> about passing this information to stmpe driver.
>
> I can't pass it in interrupts field of stmpe node, as that field
> belongs to parent
> interrupt controller of stmpe.
>
> I can't pass that from child nodes of stmpe, as we are programming the interrupt
> coming out of stmpe and not the interrupt coming out of stmpe-gpio or
> stmpe-keypad.
>
> And that's why i added these bindings. Please suggest me if i am still missing
> something.
Look into .xlate functions.
--
Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2012-11-26 11:18 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-22 18:56 [PATCH V1 1/3] mfd: stmpe: Arrange #include <header files> in alphabetical order Viresh Kumar
2012-11-22 18:56 ` [PATCH V1 2/3] mfd: stmpe-i2c: Move .driver structure fields inside {} in stmpe_i2c_driver Viresh Kumar
2012-11-26 11:15 ` Samuel Ortiz
2012-11-22 18:56 ` [PATCH V3 3/3] mfd: stmpe: Update DT support in stmpe driver Viresh Kumar
2012-11-23 9:41 ` Grant Likely
2012-11-23 17:33 ` Viresh Kumar
2012-11-26 11:18 ` Lee Jones [this message]
2012-11-26 18:40 ` Grant Likely
2012-11-27 2:40 ` Viresh Kumar
2012-11-27 3:28 ` Viresh Kumar
2012-11-27 8:40 ` Lee Jones
2012-11-27 8:46 ` Viresh Kumar
2012-11-27 19:55 ` Rabin Vincent
2012-11-28 2:13 ` Viresh Kumar
2012-11-28 9:00 ` Lee Jones
2012-11-23 10:03 ` Lee Jones
2012-11-26 11:16 ` [PATCH V1 1/3] mfd: stmpe: Arrange #include <header files> in alphabetical order Samuel Ortiz
2012-11-26 11:22 ` Viresh Kumar
2012-11-26 13:25 ` Lee Jones
2012-11-26 14:55 ` Viresh Kumar
2012-11-26 15:31 ` Lee Jones
2012-11-26 16:05 ` Samuel Ortiz
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