Re: [PATCH v2 4/4] ARM: DTS: AM43x: Add DSS node

[Mark Rutland <mark.rutland@arm.com>]

On Fri, Mar 14, 2014 at 11:07:05AM +0000, Tomi Valkeinen wrote:
> On 14/03/14 12:19, Tomi Valkeinen wrote:
> > On 14/03/14 12:14, Mark Rutland wrote:
> > 
> >> I can't see anything obviously wrong in platform_device_del. Do you have
> >> a backtrace?
> > 
> > Yes, below.
> > 
> > I can see at least drivers/usb/dwc3/dwc3-exynos.c doing the exact same thing
> > I do, so maybe I've got something wrong with the omapdss driver.
> 
> Looks to me that the devices created by of_platform_populate() are not
> unregisterable in all cases. The address resource created via
> of_platform_populate() had NULL res->parent, which causes
> release_resource to crash.

Hmm. I can't see that unregistering such devices ever works as you say,
given that __release_resource expects a non-NULL parent pointer. Either
we should be setting the parent pointer when initialising devices from
dt or we should teach __release_resource to not care. I'll have a go at
fixing that.

It looks like drivers/usb/dwc3/dwc3-exynos.c only unregisters the
top-level device, not children. This top-level device has no
IORESOURCE_{IO,MEM} resources judging by
arch/arm/boot/dts/exynos5250.dtsi, which would explain why that driver
isn't exploding: __release_resource will never get called.

Anton, Felipe: 

Does unregistering the parent ensure the children get cleaned up, or
does it leave them dangling in the dwc3-exynos driver?

Cheers,
Mark.