pinctrl: Add help text to Kconfig

The pinctrl Kconfig options should have help messages. Add this to a few
options.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/pinctrl/Kconfig b/drivers/pinctrl/Kconfig
index 30b8e452efec21793c04703260c8c9217ef439cc..918a8592bba56c899a9b07762441618f1fd5f29e 100644 (file)
--- a/drivers/pinctrl/Kconfig
+++ b/drivers/pinctrl/Kconfig
@@ -47,7 +47,10 @@ config PINMUX
        default y
        help
          This option enables pin multiplexing through the generic pinctrl
-         framework.
+         framework. Most SoCs have their own own multiplexing arrangement
+         where a single pin can be used for several functions. An SoC pinctrl
+         driver allows the required function to be selected for each pin.
+         The driver is typically controlled by the device tree.
 
 config PINCONF
        bool "Support pin configuration controllers"
@@ -86,6 +89,12 @@ config SPL_PINMUX
        help
          This option is an SPL-variant of the PINMUX option.
          See the help of PINMUX for details.
+         The pinctrl subsystem can add a substantial overhead to the SPL
+         image since it typically requires quite a few tables either in the
+         driver or in the device tree. If this is acceptable and you need
+         to adjust pin multiplexing in SPL in order to boot into U-Boot,
+         enable this option. You will need to enable device tree in SPL
+         for this to work.
 
 config SPL_PINCONF
        bool "Support pin configuration controllers in SPL"