linux-kernel - Re: [PATCH 0/7] PM / devfreq: Add NoCP devfreq-event and support busfreq on exyno5422-odroidxu3

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Message-ID: <CANAwSgRuw9ieoyu5AYFSSAcK3wgjy1-So0TA_y8bVHBa_BF7ig@mail.gmail.com>
Date:	Mon, 11 Apr 2016 09:31:38 +0530
From:	Anand Moon <linux.amoon@...il.com>
To:	Chanwoo Choi <cw00.choi@...sung.com>
Cc:	"myungjoo.ham@...sung.com" <myungjoo.ham@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Krzysztof Kozłowski <k.kozlowski@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	Markus Reichl <m.reichl@...etechno.de>,
	Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>,
	"inki.dae@...sung.com" <inki.dae@...sung.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH 0/7] PM / devfreq: Add NoCP devfreq-event and support
 busfreq on exyno5422-odroidxu3

Hi Chanwoo,

On 11 April 2016 at 07:46, Chanwoo Choi <cw00.choi@...sung.com> wrote:
> Hi Anand,
>
> On 2016년 04월 09일 03:24, Chanwoo Choi wrote:
>> Hi Anand,
>>
>> On Sat, Apr 9, 2016 at 3:11 AM, Anand Moon <linux.amoon@...il.com> wrote:
>>> Hi Chanwoo,
>>>
>
> [snip]
>
>>>>
>>>
>>> I am observing following deadlock. Both on Odroid U3 and Odroid XU4.
>>
>> Thanks for your test. I'll test it again and fix it.
>
> This possible recursive locking is fixed with following diff:
>
> Thanks for your report. I'll fix it on next patchset[1] (v9).
> [1] https://lkml.org/lkml/2016/4/8/14
>
>
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 28a9ae32d330..a4b0b02ee797 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -102,7 +102,7 @@ static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
>         if (!devfreq->governor)
>                 return -EINVAL;
>
> -       mutex_lock(&devfreq->lock);
> +       mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
>
>         ret = devfreq->governor->get_target_freq(devfreq, &freq);
>         if (ret < 0)
>
> Best Regards,
> Chanwoo Choi
>

Thanks you for these patches on devfreq.
These changes fix the warning.

Tested-by: Anand Moon <linux.amoon@...il.com>

Tested on Odroid XU4 and Odroid U3.

Best Regards
-Anand Moon