Messages in this thread | | | Date | Wed, 27 Jun 2012 10:03:16 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH] Exynos : Add support for Exynos random number generator |
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On Tue, 26 Jun 2012, Stephen Boyd wrote:
> On 06/21/12 18:39, jonghwa3.lee@samsung.com wrote: > > On 2012년 06월 21일 12:12, Stephen Boyd wrote: > > > >> On 06/20/12 19:39, jonghwa3.lee@samsung.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.
That's strange to begin with. If the usage counter is > 0 then the device shouldn't be suspended. How does this happen?
> To perform pm_runtime_get_sync() > >>> correctly, it requires to have 'suspended' status and use_count is 0.
That's not true. pm_runtime_get_sync works perfectly well when the status is "suspended" and the usage counter 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.
If the device starts out in a suspended state then the subsystem or driver should call pm_runtime_set_suspended before calling pm_runtime_enable.
Alan Stern
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