linux-kernel - Re: [PATCH V3 3/3] mfd: stmpe: Update DT support in stmpe driver

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Message-ID: <CAKohpomPMYU5H_tx1BF7TD6F7a5rp5O=xDf3r-TGZ-r9SBp3yA@mail.gmail.com>
Date:	Tue, 27 Nov 2012 14:16:48 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Lee Jones <lee.jones@...aro.org>, rabin.vincent@...ricsson.com,
	Linus Walleij <linus.walleij@...aro.org>
Cc:	Grant Likely <grant.likely@...retlab.ca>, sameo@...ux.intel.com,
	devicetree-discuss@...ts.ozlabs.org, spear-devel@...t.st.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 3/3] mfd: stmpe: Update DT support in stmpe driver

On 27 November 2012 14:10, Lee Jones <lee.jones@...aro.org> wrote:
> On Tue, 27 Nov 2012, Viresh Kumar wrote:
>> Problem is with invert polarity, which the interrupt controller is not aware of.
>> For example, suppose interrupt controller needs Rising edge interrupt, but
>> the board has inverted the line between stmpe and IC. So, we will get
>> Rising high from the routine you mentioned, but we need to generate
>> opposite of that to make it rising high.
>
> Surely that would be a hardware design error/quirk?

Yes.

> Can you give an example where this has happened?

I haven't seen this in any of SPEAr boards i have worked on. Maybe Rabin
would have, that's why he added that part of code :)

@Rabin/Linus: Do you remember why have you added this in stmpe driver:

+       if (stmpe->pdata->irq_invert_polarity)
+               icr ^= STMPE_ICR_LSB_HIGH;
+

Does somebody actually need it?

--
viresh
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