[PATCH 1/1] usb: core: Kconfig: refine the description for CONFIG_USB_OTG

[Peter Chen]

the user should only select it when the board supports HNP and SRP,
it should NOT be selected if the board only supports dual-role
switch through ID pin.

There is a discussion for it:
http://marc.info/?l=linux-arm-kernel&m=139994896101516&w=2
http://marc.info/?l=linux-usb&m=139994881701504&w=2

Signed-off-by: Peter Chen <peter.chen at freescale.com>
---
 drivers/usb/core/Kconfig |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index cb8e991..158048b 100644
--- a/drivers/usb/core/Kconfig
+++ b/drivers/usb/core/Kconfig
@@ -54,13 +54,15 @@ config USB_OTG
 	default n
 	help
 	  The most notable feature of USB OTG is support for a
-	  "Dual-Role" device, which can act as either a device
-	  or a host. The initial role is decided by the type of
-	  plug inserted and can be changed later when two dual
-	  role devices talk to each other.
+	  otg device, which can act as either a device or a host.
+	  The initial role is decided by the type of plug inserted
+	  and can be changed using HNP (Host Negotiation Protocol)
+	  later when two otg devices talk to each other.
 
 	  Select this only if your board has Mini-AB/Micro-AB
-	  connector.
+	  connector and supports HNP and SRP (Session Request Protocol).
+	  If the board only supports dual-role switch through ID
+	  pin, this configuration should not be selected.
 
 config USB_OTG_WHITELIST
 	bool "Rely on OTG Targeted Peripherals List"
-- 
1.7.8