[PATCH 1/2] drivers: amba: properly handle devices with power domains

Marek Szyprowski m.szyprowski at samsung.com
Thu Nov 26 04:55:10 PST 2015


On 2015-11-26 11:24, Ulf Hansson wrote:
> On 26 November 2015 at 09:39, Marek Szyprowski <m.szyprowski at samsung.com> wrote:
>> On 2015-11-25 19:09, Russell King - ARM Linux wrote:
>>> On Wed, Nov 25, 2015 at 02:56:10PM +0100, Ulf Hansson wrote:
>>>> On 25 November 2015 at 14:34, Marek Szyprowski <m.szyprowski at samsung.com>
>>>> wrote:
>>>>> Is ignoring dev_pm_domain_attach() return value a solution for you?
>>>> That's probably better than nothing, but I wonder if it in practice
>>>> will have any effect?
>>> If the PM domain is down, then trying to tread the ID is likely to oops
>>> the kernel.
>> In my case kernel simply hangs (no single message, even when earlyprintk is
>> enabled)
>> instead of oopsing, that's why I've submitted this patch.
> Okay.
> I suggest we go ahead and try that approach (ignoring the return
> value). It's "quick fix", but the easiest way forward to solve the
> problem.
> My only concern is if such change impacts the boot time. We should do
> some tests to see if the change is negligible, if not we should
> probably think of something else (like keeping the PM domain powered
> until late_init).
> Russell, what do you think?

Keeping PM domains powered until late_init would be a good idea 
regardless of
the problem discussed here, because I often see that pm domains are 
turned on
and off a dozen of times during typical boot of Exynos based systems.

Best regards
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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