Messages in this thread | | | Subject | Re: Odroid U3 mutex deadlock. | From | Marek Szyprowski <> | Date | Mon, 04 Jan 2016 11:38:29 +0100 |
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Hi Anand,
On 2016-01-02 06:14, Anand Moon wrote: > Hi Krzysztof > > On 14 December 2015 at 05:15, Krzysztof Kozlowski > <k.kozlowski@samsung.com> wrote: >> On 12.12.2015 13:32, Anand Moon wrote: >>> Hi Krzysztof, >>> >>> I am just observing this deadlock om my Odroid U3. >> This is not a deadlock yet, just a report from lockdep. Could be a real >> issue, could be false positive, maybe some locks miss nesting annotations. >> >> Typical information for bug report would be useful, like the exact >> version (it is mentioned in lockdep report but is it really correct?) >> and reproducibility. And of course git-bisect would be nice to have, see: >> Documentation/BUG-HUNTING >> >> Best regards, >> Krzysztof >> >> > Thanks for your inputs. I narrowed down to this commit. > ---------------------------------------------------------------------------------- > commit ec459c0c77faca53cf161830cb264e51bb1abba6 > Author: Marek Szyprowski <m.szyprowski@samsung.com> > Date: Wed Feb 4 23:44:15 2015 +0900 > > ARM: dts: add dependency between TV and LCD0 power domains for exynos4 > > TV Mixer needs both TV and LCD0 domains enabled to be fully operational. > This dependency is modelled by making TV power domains a sub-domain of > LCD0 power domain. > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Kukjin Kim <kgene@kernel.org> > ------------------------------------------------------------------------------------- > After reverting this I am not observing below lockdep warning report. > But after reverting this patch I observer another bug.
The mentioned lockdep warning is a false positive. Such warning is reported for every subdomain present in a system. As you noticed that removing dependency between power domains also removes this warning, but it will introduce real problems with power on/off sequences of graphics devices.
I will send a patch for genpd core fixing the deplock warning. Thanks for reporting the issue and pointing a good place to start digging in the source :)
Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
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