linux-kernel - Re: [patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

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Message-Id: <200712291019.39969.david-b@pacbell.net>
Date:	Sat, 29 Dec 2007 10:19:39 -0800
From:	David Brownell <david-b@...bell.net>
To:	Sam Ravnborg <sam@...nborg.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Jean Delvare <khali@...ux-fr.org>,
	eric miao <eric.y.miao@...il.com>
Subject: Re: [patch 2.6.24-rc6-mm 1/9] gpiolib: add drivers/gpio directory

On Friday 28 December 2007, Sam Ravnborg wrote:
> kconfig symbols that are "select" targets should be named "HAVE_" so in
> this case you could use HAVE_GPIO_LIB.
> This is by convention only but introduced to make it visible that this is
> a config symbol supposed to be selected.

Not widely adopted yet, but of course such things take time.


> Then on top of that the HAVE_ symbols should not have any dependencies
> so we avoid that "select" selects a symbol where the dependencies are
> not fulfilled.

That limitation of "select" still seems more buglike to me than
anything else, FWIW.  Not that it matters in this case.
 

> In your case you could just use
> obj-y += gpio/
> 
> in the Makefile and then there is no need to actually reference the
> kconfig symbol.

No, that just shifts the reference into the drivers/gpio Makefilee.

 
> ccflags-$(CONFIG_DEBUG_GPIO) := -DDEBUG

Another new convention.  :)

Pretty much like the folowing, then?

- Dave


==============	CUT HERE
Kbuild/Kconfig feedback from Sam Ravnborg, adopting new conventions:

  - HAVE_* for Kconfig symbols that platforms will select

  - Descend into drivers/gpio unconditionally, letting the Makefile
    sort out the differences

  - Use "ccflags-$(CONGIF_DEBUG_GPIO) += -DDEBUG" instead of
    those ugly (but traditional) conditionals.

Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
---
 arch/arm/Kconfig           |    4 +-
 arch/avr32/Kconfig         |    2 +-
 drivers/Makefile           |    2 +-
 drivers/gpio/Kconfig       |    4 ++--
 drivers/gpio/Makefile      |   10 ++++------
 include/asm-generic/gpio.h |    2 +-
 6 files changed, 10 insertions(+), 12 deletions(-)

--- at91.orig/arch/arm/Kconfig
+++ at91/arch/arm/Kconfig
@@ -346,7 +346,7 @@ config ARCH_PXA
 	select GENERIC_GPIO
 	select GENERIC_TIME
 	select GENERIC_CLOCKEVENTS
-	select GPIO_LIB
+	select HAVE_GPIO_LIB
 	help
 	  Support for Intel/Marvell's PXA2xx/PXA3xx processor line.
 
--- at91.orig/arch/avr32/Kconfig
+++ at91/arch/avr32/Kconfig
@@ -80,7 +80,7 @@ config PLATFORM_AT32AP
 	select SUBARCH_AVR32B
 	select MMU
 	select PERFORMANCE_COUNTERS
-	select GPIO_LIB
+	select HAVE_GPIO_LIB
 
 choice
 	prompt "AVR32 CPU type"
--- at91.orig/drivers/Makefile
+++ at91/drivers/Makefile
@@ -5,7 +5,7 @@
 # Rewritten to use lists instead of if-statements.
 #
 
-obj-$(CONFIG_GPIO_LIB)		+= gpio/
+obj-y				+= gpio/
 obj-$(CONFIG_PCI)		+= pci/
 obj-$(CONFIG_PARISC)		+= parisc/
 obj-$(CONFIG_RAPIDIO)		+= rapidio/
--- at91.orig/drivers/gpio/Kconfig
+++ at91/drivers/gpio/Kconfig
@@ -2,7 +2,7 @@
 # GPIO infrastructure and expanders
 #
 
-config GPIO_LIB
+config HAVE_GPIO_LIB
 	bool
 	help
 	  Platforms select gpiolib if they use this infrastructure
@@ -10,7 +10,7 @@ config GPIO_LIB
 	  into SOC processors.
 
 menu "GPIO Support"
-	depends on GPIO_LIB
+	depends on HAVE_GPIO_LIB
 
 config DEBUG_GPIO
 	bool "Debug GPIO calls"
--- at91.orig/drivers/gpio/Makefile
+++ at91/drivers/gpio/Makefile
@@ -1,12 +1,10 @@
 # gpio support: dedicated expander chips, etc
 
+ccflags-$(CONGIF_DEBUG_GPIO)	+= -DDEBUG
+
+obj-$(CONFIG_HAVE_GPIO_LIB)	+= gpiolib.o
+
 obj-$(CONFIG_GPIO_MCP23S08)	+= mcp23s08.o
 obj-$(CONFIG_GPIO_PCA9539)	+= pca9539.o
 obj-$(CONFIG_GPIO_PCF857X)	+= pcf857x.o
 
-ifeq ($(CONFIG_DEBUG_GPIO),y)
-EXTRA_CFLAGS += -DDEBUG
-endif
-
-obj-$(CONFIG_GPIO_LIB) += gpiolib.o
-
--- at91.orig/include/asm-generic/gpio.h
+++ at91/include/asm-generic/gpio.h
@@ -1,7 +1,7 @@
 #ifndef _ASM_GENERIC_GPIO_H
 #define _ASM_GENERIC_GPIO_H
 
-#ifdef CONFIG_GPIO_LIB
+#ifdef CONFIG_HAVE_GPIO_LIB
 
 /* Platforms may implement their GPIO interface with library code,
  * at a small performance cost for non-inlined operations and some
--
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