linux-kernel - Re: [PATCH v11 10/27] iommu/exynos: use managed device helper functions

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Message-id: <20140319175927.a3feadcacbffe80eca1d3421@samsung.com>
Date:	Wed, 19 Mar 2014 17:59:27 +0900
From:	Cho KyongHo <pullip.cho@...sung.com>
To:	Tomasz Figa <t.figa@...sung.com>
Cc:	Sachin Kamat <sachin.kamat@...aro.org>,
	Linux ARM Kernel <linux-arm-kernel@...ts.infradead.org>,
	Linux DeviceTree <devicetree@...r.kernel.org>,
	Linux IOMMU <iommu@...ts.linux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux Samsung SOC <linux-samsung-soc@...r.kernel.org>,
	Antonios Motakis <a.motakis@...tualopensystems.com>,
	Grant Grundler <grundler@...omium.org>,
	Joerg Roedel <joro@...tes.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Prathyush <prathyush.k@...sung.com>,
	Rahul Sharma <rahul.sharma@...sung.com>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Varun Sethi <Varun.Sethi@...escale.com>
Subject: Re: [PATCH v11 10/27] iommu/exynos: use managed device helper functions

On Tue, 18 Mar 2014 16:14:53 +0100, Tomasz Figa wrote:
> On 18.03.2014 12:09, Cho KyongHo wrote:
> > On Fri, 14 Mar 2014 20:52:43 +0530, Sachin Kamat wrote:
> >> Hi KyongHo,
> >>
> >> On 14 March 2014 10:35, Cho KyongHo <pullip.cho@...sung.com> wrote:
> >>> This patch uses managed device helper functions in the probe().
> >>>
> >>> Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
> >>> ---
> >> [snip]
> >>
> >>> +       data->clk = devm_clk_get(dev, "sysmmu");
> >>> +       if (IS_ERR(data->clk)) {
> >>> +               dev_info(dev, "No gate clock found!\n");
> >>> +               data->clk = NULL;
> >>> +       }
> >>
> >> Why aren't you returning from here upon error?
> >
> > It is for the case of a System MMU which does not need clock gating.
> >
> 
> Are there really such cases?
> 

Yes.
Especially in the case of initial stage of new SoC development.

I have experianced some software workaround for H/W restriction
needs prevention of clock gating for some devices.

Regards,

KyongHo
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