linux-kernel - Re: [PATCH 2/5] thermal: exynos: cleanup of clk err check for exynos_tmu

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Date:   Wed, 18 Jul 2018 01:38:17 +0530
From:   Anand Moon <linux.amoon@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Kukjin Kim <kgene@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Linux PM list <linux-pm@...r.kernel.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH 2/5] thermal: exynos: cleanup of clk err check for exynos_tmu_work

Hi Krzysztof,

On 17 July 2018 at 17:54, Krzysztof Kozlowski <krzk@...nel.org> wrote:
> On 17 July 2018 at 12:12, Anand Moon <linux.amoon@...il.com> wrote:
>> cleanup err check in exynos_tmu_work as clk internal
>> framework will perform if clk is enable/disable
>> so drop the double check of IS_ERR and other such references.
>
> I do not understand the statement. Clock framework will perform if clk
> is enable/disable? How clock can be "enable" or "disable"? You mean
> gate clock? you mean clock pointer is an ERR pointer?
>

if (!IS_ERR(data->clk_sec))
check if the pointer is valid or not
this check is again performed in
clk_enable.

>> CC: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
>> Signed-off-by: Anand Moon <linux.amoon@...il.com>
>> ---
>>  drivers/thermal/samsung/exynos_tmu.c | 19 ++++++-------------
>>  1 file changed, 6 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
>> index 0164c9e..2dbde97 100644
>> --- a/drivers/thermal/samsung/exynos_tmu.c
>> +++ b/drivers/thermal/samsung/exynos_tmu.c
>> @@ -300,8 +300,7 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
>>
>>         mutex_lock(&data->lock);
>>         clk_enable(data->clk);
>> -       if (!IS_ERR(data->clk_sec))
>> -               clk_enable(data->clk_sec);
>> +       clk_enable(data->clk_sec);
>>
>>         status = readb(data->base + EXYNOS_TMU_REG_STATUS);
>>         if (!status) {
>> @@ -334,8 +333,7 @@ static int exynos_tmu_initialize(struct platform_device *pdev)
>>  err:
>>         clk_disable(data->clk);
>>         mutex_unlock(&data->lock);
>> -       if (!IS_ERR(data->clk_sec))
>> -               clk_disable(data->clk_sec);
>> +       clk_disable(data->clk_sec);
>>  out:
>>         return ret;
>>  }
>> @@ -789,19 +787,16 @@ static void exynos_tmu_work(struct work_struct *work)
>>         struct exynos_tmu_data *data = container_of(work,
>>                         struct exynos_tmu_data, irq_work);
>>
>> -       if (!IS_ERR(data->clk_sec))
>> -               clk_enable(data->clk_sec);
>> -       if (!IS_ERR(data->clk_sec))
>> -               clk_disable(data->clk_sec);
>> -
>>         thermal_zone_device_update(data->tzd, THERMAL_EVENT_UNSPECIFIED);
>>
>>         mutex_lock(&data->lock);
>>         clk_enable(data->clk);
>> +       clk_enable(data->clk_sec);
>
> You are changing here the logic completely. Before the "enable" was
> followed immediately by "disable". Now you are moving disable
> somewhere else... All this looks suspicious...

I chose to move enable/disable of clk_sec this under the mutex lock for safe
which dose the same sequence with different order.

Second approach:
We should get rid of clk_enable/disable in exynos_tmu_work
as this looks unnecessary for toggle clk's on every update.

Best Regards
-Anand