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

[Felipe Balbi <balbi@ti.com>]

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On Fri, Mar 14, 2014 at 02:07:45PM +0000, Mark Rutland wrote:
> 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?

you should platform_device_unregister() for each children and
dwc3-exynos does that just fine:

167 static int dwc3_exynos_remove(struct platform_device *pdev)
168 {
169         struct dwc3_exynos      *exynos = platform_get_drvdata(pdev);
170 
171         device_for_each_child(&pdev->dev, NULL, dwc3_exynos_remove_child);
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

172         platform_device_unregister(exynos->usb2_phy);
173         platform_device_unregister(exynos->usb3_phy);
174 
175         clk_disable_unprepare(exynos->clk);
176 
177         return 0;
178 }

for each child of this device, we call dwc3_exynos_remove_child(), which
will:


94 static int dwc3_exynos_remove_child(struct device *dev, void *unused)
95 {
96         struct platform_device *pdev = to_platform_device(dev);
97 
98         platform_device_unregister(pdev);
99 
100        return 0;
101 }

-- 
balbi

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