linux-kernel - Re: [PATCH] Exynos : Add support for Exynos random number generator

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Date:	Tue, 26 Jun 2012 12:32:14 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	jonghwa3.lee@...sung.com
CC:	linux-kernel@...r.kernel.org, Matt Mackall <mpm@...enic.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Julia Lawall <Julia.Lawall@...6.fr>,
	Jamie Iles <jamie@...ieiles.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Linux PM mailing list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] Exynos : Add support for Exynos random number generator

On 06/21/12 18:39, jonghwa3.lee@...sung.com wrote:
> On 2012년 06월 21일 12:12, Stephen Boyd wrote:
>
>> On 06/20/12 19:39, jonghwa3.lee@...sung.com wrote:
>>>>> +static int exynos_init(struct hwrng *rng)
>>>>> +{
>>>>> +	struct exynos_rng *exynos_rng = container_of(rng,
>>>>> +						struct exynos_rng, rng);
>>>>> +	int i;
>>>>> +	int ret = 0;
>>>>> +	u32 PRND_SEED[5];
>>>>> +
>>>>> +	pm_runtime_put_noidle(exynos_rng->dev);
>>>>> +	pm_runtime_get_sync(exynos_rng->dev);
>>>> This looks very odd. Why are you calling pm_runtime_put_noidle()?
>>>>
>>> When this callback function is called, the status of power state is
>>> 'suspended' and use_count is 1. To perform pm_runtime_get_sync()
>>> correctly, it requires to have 'suspended' status and use_count is 0.
>>> Thus i force to decrease use_count only with using
>>> pm_runtime_put_noidle. I know it looks odd, but i couldn't find better
>>> way. Otherwise it can use clk_enable() directly, but i think that it
>>> isn't good neither.
>> Is the device suspended initially at probe? If so can you set the state
>> of the device to suspended?
>>
>
> Yes, it suspended already at the initial of probing. But i can't get
> your point, you want to me to make device suspended?

I mean to say you should probably call pm_runtime_set_suspended() during
probe. But I'm not sure and I would defer to people more familiar with
runtime pm.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

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