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

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Message-ID: <CAJKOXPdMEp1r_K3Qa_iztfvKg61BEn4TejtoDwpq_Yf1CnyRAg@mail.gmail.com>
Date:   Tue, 17 Jul 2018 22:11:21 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Anand Moon <linux.amoon@...il.com>
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

On 17 July 2018 at 22:08, Anand Moon <linux.amoon@...il.com> wrote:
> 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.

This should be then written in commit msg.

>>> 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.

I already sent a cleanup for this:
https://patchwork.kernel.org/patch/10529971/

Best regards,
Krzysztof