On Tue, Aug 31, 2010 at 2:37 AM, Anton Vorontsov [off-list ref] w=
rote:

On Tue, Aug 31, 2010 at 02:03:44AM -0600, Grant Likely wrote:

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On Tue, Aug 24, 2010 at 01:26:23PM +0400, Anton Vorontsov wrote:

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With CONFIG_GPIOLIB=3Dn, the 'struct gpio_chip' is not declared,
so the following pops up on PowerPC:

=A0 cc1: warnings being treated as errors
=A0 In file included from arch/powerpc/platforms/52xx/mpc52xx_common.c=

:19:

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=A0 include/linux/of_gpio.h:74: warning: 'struct gpio_chip' declared
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 inside par=

ameter list

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=A0 include/linux/of_gpio.h:74: warning: its scope is only this defini=

tion

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=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 or declara=

tion, which is probably not what

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=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 you want
=A0 include/linux/of_gpio.h:75: warning: 'struct gpio_chip' declared
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 inside par=

ameter list

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=A0 make[2]: *** [arch/powerpc/platforms/52xx/mpc52xx_common.o] Error =

1

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This patch fixes the issue by providing the proper forward declaration=

.

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Signed-off-by: Anton Vorontsov <redacted>

This doesn't actually solve the problem, and gpiochip should
remain undefined when CONFIG_GPIOLIB=3Dn to catch exactly these
build failures. =A0The real problem is that I merged a change
into the mpc5200 code that required CONFIG_GPIOLIB be enabled
without reflecting that requirement in Kconfig.

No, look closer. The error is in of_gpio.h, and it's perfectly
fine to include it w/o GPIOLIB=3Dy.

Looking even closer, we're both wrong.  You're right I didn't look
carefully enough, and the error is in of_gpio.h, not the .c file.

However, it is not okay to get the definitions from of_gpio.h when
CONFIG_GPIOLIB=3Dn.  If GPIOLIB, or more specifically OF_GPIO isn't set,
then the of_gpio.h definitions should either not be defined, or should
be defined as empty stubs (where appropriate).

So, instead of adding a forward declarations of the struct, the
correct thing I think to do is to #ifdef out the contents of of_gpio.h
when GPIOLIB isn't selected so that extra #includes are completely
benign.  I've been doing the same thing on the other linux/of*.h
headers.  I've got a patch in my tree that I'm testing right now and
I'll post later today.

g.

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---

On Tue, Aug 24, 2010 at 04:26:08PM +1000, Benjamin Herrenschmidt wrote=

:

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I get that with my current stuff:

cc1: warnings being treated as errors
In file included from [..]/mpc52xx_common.c:19:
of_gpio.h:74: error: =91struct gpio_chip=92 declared inside paramete=

r list

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[...]

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make[3]: *** Waiting for unfinished jobs....

That's because with GPIOCHIP=3Dn no one declares struct gpio_chip.

It should be either of_gpio.h or gpio.h. Let's make it gpio.h, as
this feels more generic, and we already have some !GPIOLIB handling
in there.

=A0include/linux/gpio.h | =A0 =A06 ++++++
=A01 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index 03f616b..85207d2 100644
--- a/include/linux/gpio.h
+++ b/include/linux/gpio.h

@@ -15,6 +15,12 @@

=A0struct device;

=A0/*
+ * Some code might rely on the declaration. Still, it is illegal
+ * to dereference it for !GPIOLIB case.
+ */
+struct gpio_chip;
+
+/*
=A0 * Some platforms don't support the GPIO programming interface.
=A0 *
=A0 * In case some driver uses it anyway (it should normally have
--
1.7.0.5

--
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2

--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.