Messages in this thread | | | Date | Wed, 19 Mar 2014 13:08:42 +0100 | From | Tomasz Figa <> | Subject | Re: [PATCH v11 10/27] iommu/exynos: use managed device helper functions |
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On 19.03.2014 10:01, Sachin Kamat wrote: > On 19 March 2014 14:29, Cho KyongHo <pullip.cho@samsung.com> wrote: >> 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@samsung.com> wrote: >>>>>> This patch uses managed device helper functions in the probe(). >>>>>> >>>>>> Signed-off-by: Cho KyongHo <pullip.cho@samsung.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. > > So aren't these basically some exceptions/hacks rather than the usual way > of functioning of the device? >
This actually raises a good question, whether we really need to support such early development SoC versions in mainline.
Another thing is that if you need to assure that a clock is ungated, you must acquire it and prepare_enable explicitly, so I don't think this kind of handling is correct.
Best regards, Tomasz
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