On Fri, Sep 02, 2016 at 04:11:46PM +0300, Vladimir Zapolskiy wrote:

Hi Shawn, Fabio,

On 08/20/2016 01:10 AM, Vladimir Zapolskiy wrote:

quoted

The change establishes a connection between on-SoC IOMUX controller(s)
and GPIO controllers found on some SoC from Freescale/NXP iMX series,
if a GPIO controller device node contains common gpio-ranges information.

The change is backward compatible with respect to potentially not updated
outdated DTB data without gpio-ranges propery, for such boards the only
functional change is lowered initcall priority of GPIO controller driver,
which in general anyway is exected to be used only after pinctrl/pinmux
controller.

If this change is applied the next interesting applications may be done
as a follow-up work, for example switching pad function to GPIO on gpiod
request, converting iomux controller driver to strict type and so on.

For actual values of gpio-ranges properties please reference series
"ARM: dts: imx: add gpio-ranges properties to some iMX GPIO controllers"
http://archive.arm.linux.org.uk/lurker/message/20160819.220621.86d845d1.en.html

Deepak Das (1):
 gpio: mxc: lower level of gpio_mxc_init() initcall

Vladimir Zapolskiy (2):
 pinctrl: imx: accept gpio request/free from pinctrl
 gpio: mxc: add generic gpio request/free callbacks to pinctrl

drivers/gpio/gpio-mxc.c                 | 7 ++++++-
drivers/pinctrl/freescale/pinctrl-imx.c | 4 ++--
2 files changed, 8 insertions(+), 3 deletions(-)

no comments so far, please could you express your concerns about
this change? IMHO it would be nice to have this feature enabled
in v4.9.

I assume that the most worrisome commit is the change of GPIO controller
driver init level, but I belive it is safe enough, no?

If I understand it correctly, with the change, most of GPIO client
device drivers use the same init level as GPIO driver.  So we are not
sure if GPIO driver is ready when client drivers try to request GPIO.
It shouldn't be a problem if every client driver handle the failure
with deferred probing, but I'm not sure that's the case now.

Shawn