Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756256Ab2F0ODT (ORCPT ); Wed, 27 Jun 2012 10:03:19 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:57555 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751850Ab2F0ODR (ORCPT ); Wed, 27 Jun 2012 10:03:17 -0400 Date: Wed, 27 Jun 2012 10:03:16 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Stephen Boyd cc: jonghwa3.lee@samsung.com, , Matt Mackall , Herbert Xu , Nicolas Ferre , Julia Lawall , Jamie Iles , Kyungmin Park , Linux PM mailing list Subject: Re: [PATCH] Exynos : Add support for Exynos random number generator In-Reply-To: <4FEA0E3E.2070804@codeaurora.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2154 Lines: 56 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/