linux-kernel - Re: [PATCH v11 15/27] iommu/exynos: use convenient macro to handle gate clocks

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Message-id: <53284527.8010903@samsung.com>
Date:	Tue, 18 Mar 2014 14:07:51 +0100
From:	Tomasz Figa <t.figa@...sung.com>
To:	Sachin Kamat <sachin.kamat@...aro.org>,
	Cho KyongHo <pullip.cho@...sung.com>
Cc:	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 15/27] iommu/exynos: use convenient macro to handle
 gate clocks

On 18.03.2014 12:18, Sachin Kamat wrote:
> On 18 March 2014 16:33, Cho KyongHo <pullip.cho@...sung.com> wrote:
>> On Fri, 14 Mar 2014 22:27:59 +0530, Sachin Kamat wrote:
>>>   Hi KyongHo,
>>>
>>> On 14 March 2014 19:13, Tomasz Figa <t.figa@...sung.com> wrote:
>>>> Hi KyongHo,
>>>>
>>>>
>>>> On 14.03.2014 06:09, Cho KyongHo wrote:
>>>>>
>>>>> exynos-iommu driver must care about master H/W's gate clock as well as
>>>>> System MMU's gate clock. To enhance readability of the source code,
>>>>> macros to gate/ungate those clocks are defined.
>>>>>
>>>>> Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
>>>>> ---
>>>>>    drivers/iommu/exynos-iommu.c |   34 ++++++++++++++++++++++------------
>>>>>    1 file changed, 22 insertions(+), 12 deletions(-)
>>>>>
>>>>> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
>>>>> index 71e77f1..cef62d0 100644
>>>>> --- a/drivers/iommu/exynos-iommu.c
>>>>> +++ b/drivers/iommu/exynos-iommu.c
>>>>> @@ -101,6 +101,16 @@
>>>>>    #define REG_PB1_SADDR         0x054
>>>>>    #define REG_PB1_EADDR         0x058
>>>>>
>>>>> +#define __clk_gate_ctrl(data, clk, en) do {            \
>>>>> +               if (data->clk)                          \
>>>>> +                       clk_##en##able(data->clk);      \
>>>>> +       } while (0)
>>>>> +
>>>>> +#define __sysmmu_clk_enable(data)      __clk_gate_ctrl(data, clk, en)
>>>>> +#define __sysmmu_clk_disable(data)     __clk_gate_ctrl(data, clk, dis)
>>>>> +#define __master_clk_enable(data)      __clk_gate_ctrl(data, clk_master,
>>>>> en)
>>>>> +#define __master_clk_disable(data)     __clk_gate_ctrl(data, clk_master,
>>>>> dis)
>>>>> +
>>>>
>>>>
>>>> I'd say that such macros only obfuscate code, without any gains, as you can
>>>> see in diffstat - this patch adds more lines than it removes.
>>>>
>>>> Please drop this change.
>>>
>>>   I agree with Tomasz here.
>>>
>>
>> Are you concerning about using macros or more insertions than deletions?
>
> It is just making the code more difficult to read and understand.

Especially when hiding accesses to struct fields inside and doing fancy 
stuff like concatenations.

Best regards,
Tomasz
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