From: t.figa@samsung•com (Tomasz Figa)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v11 10/27] iommu/exynos: use managed device helper functions
Date: Wed, 19 Mar 2014 13:08:42 +0100 [thread overview]
Message-ID: <532988CA.4000008@samsung.com> (raw)
In-Reply-To: <CAK9yfHxxo2eFh38gPZkpYf1ueBWySWqPzgLV_tSSykzHhNzN8g@mail.gmail.com>
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
next prev parent reply other threads:[~2014-03-19 12:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-14 5:05 [PATCH v11 10/27] iommu/exynos: use managed device helper functions Cho KyongHo
2014-03-14 13:28 ` Tomasz Figa
2014-03-18 10:38 ` Cho KyongHo
2014-03-18 15:12 ` Tomasz Figa
2014-03-18 23:59 ` Jingoo Han
2014-03-19 8:56 ` Cho KyongHo
2014-03-14 15:22 ` Sachin Kamat
2014-03-18 11:09 ` Cho KyongHo
2014-03-18 15:14 ` Tomasz Figa
2014-03-19 8:59 ` Cho KyongHo
2014-03-19 9:01 ` Sachin Kamat
2014-03-19 12:08 ` Tomasz Figa [this message]
2014-03-20 10:03 ` Cho KyongHo
2014-03-20 10:44 ` Tomasz Figa
2014-03-21 4:49 ` Cho KyongHo
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