On Thu, Sep 8, 2016 at 3:48 AM, Vladimir Zapolskiy
[off-list ref] wrote:

In general situation on-SoC GPIO controller drivers should be probed
after pinctrl/pinmux controller driver, because on-SoC GPIOs utilize a
pin/pad as a resource provided and controlled by pinctrl subsystem.

This is stated in multiple places, e.g. from drivers/Makefile:

  GPIO must come after pinctrl as gpios may need to mux pins etc

Looking at Freescale iMX SoC series specifics, imx*_pinctrl_init()
functions are called at arch_initcall and postcore_initcall init
levels, so the change of initcall level for gpio-mxc driver from
postcore_initcall to subsys_initcall level is sufficient. Also note
that the most of GPIO controller drivers settled at subsys_initcall
level.

If pinctrl subsystem manages pads with GPIO functions, the change is
needed to avoid unwanted driver probe deferrals during kernel boot.

Signed-off-by: Vladimir Zapolskiy <redacted>
---
Changes from v1 to v2:
* replaced by a change with better commit description and which
  moves gpio_mxc_init() call to subsys_initcall() instead of
  apparently too late device_initcall(), this mitigates Shawn's
  expressed concern about the change.

Patch applied with Shawn's ACK.

Yours,
Linus Walleij