linux-kernel - Re: [PATCH] Input: eeti_ts: Mark as CONFIG

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Date:	Tue, 10 Apr 2012 11:10:47 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Olof Johansson <olof@...om.net>
Cc:	Sven Neumann <s.neumann@...mfeld.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Haojian Zhuang <haojian.zhuang@...vell.com>,
	linux-kernel@...r.kernel.org, Daniel Mack <daniel@...aq.de>,
	linux-input@...r.kernel.org, Daniel Mack <zonque@...il.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] Input: eeti_ts: Mark as CONFIG_BROKEN

On Sat, Apr 07, 2012 at 01:32:31PM -0700, Olof Johansson wrote:
> Haojian, I think it was probably premature to do the multiplatform
> change like that, since it means that a PXA-only kernel has no mapping
> from irq_to_gpio to pxa_irq_to_gpio. Can you please address this as a
> fix for 3.4?

Please fix ezx-pcap instead - it's broken as it currently stands by using
irq_to_gpio(), and it's one reason why my randconfig builds on OMAP fail.

The big problem is - what does this do:

        do {
...
        } while (gpio_get_value(irq_to_gpio(pcap->spi->irq)));

if pcap->spi->irq has no GPIO associated with the interrupt?  irq_to_gpio()
probably returns some random number which might be some other GPIO in the
system, and gpio_get_value() could oops if irq_to_gpio returns a negative
or large positive number.  To put it another way, according to the above
code, irq_to_gpio() must always return a valid gpio for the IRQ even if
the IRQ doesn't have a GPIO associated with it.

This is a fine illustration of why irq_to_gpio() is just plain broken in
its design.
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