Re: pxa_defconfig runtime failures due to 'ARM: pxa: activate pinctrl for device-tree machines'

From: Robert Jarzmik
Date: Sat May 28 2016 - 04:24:44 EST

Guenter Roeck <linux@xxxxxxxxxxxx> writes:

> Hi,
> your mainline commit f806dac5938b ("ARM: pxa: activate pinctrl for device-tree
> machines") causes various non-devicetree systems to fail with the following
> error messages when running a pxa_defconfig image.
Ah yes, you're right.

> During boot:
> Can't request reset_gpio
> At reboot:
> reboot: Restarting system
> ------------[ cut here ]------------
> kernel BUG at arch/arm/mach-pxa/reset.c:59!
> ...
> Added logging shows that the error seen when trying to request the reset gpio
> is -EPROBE_DEFER, and that the pxa gpio driver is not instantiated.
> This is seen when attempting to run akita, borzoi, spitz, terrier, or tosa
> in qemu with pxa_defconfig. Reverting your patch fixes the problem.
> Is this on purpose ?
Well no :)
The real reason behind is that gpio handling for pxa in its current state cannot
be built for _both_ a devicetree machine (ie. pxa-dt.c) and a non devicetree
machine (ie. corgi, tosa, ...).

This is turn is because for devicetree a pinctrl is enforced for the machine,
and a pinctrl driver is required. If it's not available, pxa_gpio_request()
fails on pinctrl_request_gpio() and returns -EPROBE_DEFER.

Now the true chicken and egg problem is than machine files,
ie. arch/arm/mach-pxa/xxx.c are using gpio before the drivers are probed, in the
init_machine() function, and that's why pinctrl/gpio for legacy machine files is
a bit difficult.

> Unless I am missing something, it effectively means that
> pxa_defconfig no longer works for pxa3xx systems, since those do not support
> devicetree (or at least there is no devicetree file which includes
> pxa3xx.dtsi).
I'd rather say that pxa_defconfig doesn't work anymore on any legacy system.
Its first purpose was to ensure compilation coverage of all legacy pxa systems.
Its second one was to have a single kernel bootable on all legacy pxa systems.

Therefore, would you tell me if the patch in [1] fixes your issue ?



[1] One solution