Patch "ARM: dts: kirkwood: fix pin-muxing of MPP7 on OpenBlocks A7" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

ARM: dts: kirkwood: fix pin-muxing of MPP7 on OpenBlocks A7

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-dts-kirkwood-fix-pin-muxing-of-mpp7-on-openblocks-a7.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Thomas Petazzoni <[email protected]>
Date: Thu, 4 Jan 2018 17:53:12 +0100
Subject: ARM: dts: kirkwood: fix pin-muxing of MPP7 on OpenBlocks A7

From: Thomas Petazzoni <[email protected]>

commit 56aeb07c914a616ab84357d34f8414a69b140cdf upstream.

MPP7 is currently muxed as "gpio", but this function doesn't exist for MPP7, only "gpo" is available. This causes the following error:

kirkwood-pinctrl f1010000.pin-controller: unsupported function gpio on pin mpp7 pinctrl core: failed to register map default (6): invalid type given kirkwood-pinctrl f1010000.pin-controller: error claiming hogs: -22 kirkwood-pinctrl f1010000.pin-controller: could not claim hogs: -22 kirkwood-pinctrl f1010000.pin-controller: unable to register pinctrl driver
kirkwood-pinctrl: probe of f1010000.pin-controller failed with error -22

So the pinctrl driver is not probed, all device drivers (including the UART driver) do a -EPROBE_DEFER, and therefore the system doesn't really boot (well, it boots, but with no UART, and no devices that require pin-muxing).

Back when the Device Tree file for this board was introduced, the definition was already wrong. The pinctrl driver also always described as "gpo" this function for MPP7. However, between Linux 4.10 and 4.11, a hog pin failing to be muxed was turned from a simple warning to a hard error that caused the entire pinctrl driver probe to bail out. This is probably the result of commit 6118714275f0a ("pinctrl:
core: Fix pinctrl_register_and_init() with pinctrl_enable()").

This commit fixes the Device Tree to use the proper "gpo" function for MPP7, which fixes the boot of OpenBlocks A7, which was broken since Linux 4.11.

---
 arch/arm/boot/dts/kirkwood-openblocks_a7.dts |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

@@ -53,7 +53,8 @@
 		};
 
 		pinctrl: pin-controller@10000 {
-			pinctrl-0 = <&pmx_dip_switches &pmx_gpio_header>;
+			pinctrl-0 = <&pmx_dip_switches &pmx_gpio_header
+				     &pmx_gpio_header_gpo>;
 			pinctrl-names = "default";
 
 			pmx_uart0: pmx-uart0 {

@@ -85,11 +86,16 @@
 			 * ground.
 			 */
 			pmx_gpio_header: pmx-gpio-header {
-				marvell,pins = "mpp17", "mpp7", "mpp29", "mpp28",
+				marvell,pins = "mpp17", "mpp29", "mpp28",
 					       "mpp35", "mpp34", "mpp40";
 				marvell,function = "gpio";
 			};
 
+			pmx_gpio_header_gpo: pxm-gpio-header-gpo {
+				marvell,pins = "mpp7";
+				marvell,function = "gpo";
+			};
+
 			pmx_gpio_init: pmx-init {
 				marvell,pins = "mpp38";
 				marvell,function = "gpio";

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/arm-dts-kirkwood-fix-pin-muxing-of-mpp7-on-openblocks-a7.patch