[PATCH] i2c: Suggest N for rare devices in Kconfig

Improve the Kconfig help text of the follwing i2c drivers:
* busses/i2c-pca-isa.c
* chips/pcf8574.c
* chips/pcf8591.c
These are hard to detect and building them into the kernel
results in long delays at boot.

March 2006, thread "I2C_PCA_ISA causes boot delays"
http://marc.theaimsgroup.com/?l=linux-kernel&m=114360399415744&w=2

April 2006, thread "i2c-related 1-minute hang during bootup"
http://marc.theaimsgroup.com/?l=linux-kernel&m=114640992330721&w=2

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/i2c/busses/Kconfig

@@ -503,6 +503,7 @@ config I2C_PCA_ISA
 	tristate "PCA9564 on an ISA bus"
 	depends on I2C
 	select I2C_ALGOPCA
+	default n
 	help
 	  This driver supports ISA boards using the Philips PCA 9564
 	  Parallel bus to I2C bus controller
@@ -510,6 +511,11 @@ config I2C_PCA_ISA
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-pca-isa.
 
+	  This device is almost undetectable and using this driver on a
+	  system which doesn't have this device will result in long
+	  delays when I2C/SMBus chip drivers are loaded (e.g. at boot
+	  time).  If unsure, say N.
+
 config I2C_MV64XXX
 	tristate "Marvell mv64xxx I2C Controller"
 	depends on I2C && MV64X60 && EXPERIMENTAL

drivers/i2c/chips/Kconfig

@@ -39,6 +39,7 @@ config SENSORS_EEPROM
 config SENSORS_PCF8574
 	tristate "Philips PCF8574 and PCF8574A"
 	depends on I2C && EXPERIMENTAL
+	default n
 	help
 	  If you say yes here you get support for Philips PCF8574 and 
 	  PCF8574A chips.
@@ -46,6 +47,9 @@ config SENSORS_PCF8574
 	  This driver can also be built as a module.  If so, the module
 	  will be called pcf8574.
 
+	  These devices are hard to detect and rarely found on mainstream
+	  hardware.  If unsure, say N.
+
 config SENSORS_PCA9539
 	tristate "Philips PCA9539 16-bit I/O port"
 	depends on I2C && EXPERIMENTAL
@@ -59,12 +63,16 @@ config SENSORS_PCA9539
 config SENSORS_PCF8591
 	tristate "Philips PCF8591"
 	depends on I2C && EXPERIMENTAL
+	default n
 	help
 	  If you say yes here you get support for Philips PCF8591 chips.
 
 	  This driver can also be built as a module.  If so, the module
 	  will be called pcf8591.
 
+	  These devices are hard to detect and rarely found on mainstream
+	  hardware.  If unsure, say N.
+
 config ISP1301_OMAP
 	tristate "Philips ISP1301 with OMAP OTG"
 	depends on I2C && ARCH_OMAP_OTG