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Subject: Re: [v4,7/7] thermal: mediatek: use spinlock to protect PTPCORESEL
To:     Michael Kao <michael.kao@mediatek.com>
Cc:     Matthias Brugger <matthias.bgg@gmail.com>,
        Zhang Rui <rui.zhang@intel.com>,
        Eduardo Valentin <edubezval@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>, hsinyi@chromium.org,
        linux-pm@vger.kernel.org, srv_heupstream@mediatek.com,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
References: <20200323121537.22697-1-michael.kao@mediatek.com>
 <20200323121537.22697-8-michael.kao@mediatek.com>
 <1afbf412-fbeb-8abe-66d8-bd7ac4e9dd83@linaro.org>
 <1591329023.12739.0.camel@mtksdccf07>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
Message-ID: <4c9e9abf-1f87-ae68-3827-22df52adfd19@linaro.org>
Date:   Tue, 7 Jul 2020 10:13:46 +0200
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On 05/06/2020 05:50, Michael Kao wrote:
> On Fri, 2020-05-22 at 17:36 +0200, Daniel Lezcano wrote:
>> On 23/03/2020 13:15, Michael Kao wrote:
>>> From: "michael.kao" <michael.kao@mediatek.com>
>>>
>>> The driver of thermal and svs will use the
>>> same register for the project which should select
>>> bank before reading sensor value.
>>
>> Here there is a design problem AFAICT. The sensor should not be using
>> external locks.
>>
> The PTPCORESEL is a common register used by svs and thermal.
> The thermal need to ensure PTPCORESEL register will not be changed by
> svs when thermal switch bank to read raw data of temperature.
> So we use svs_lock to make sure there is no conflict between the two
> drivers.

Why not use regmap ?

>>> Signed-off-by: Michael Kao <michael.kao@mediatek.com>
>>> ---
>>>  drivers/thermal/mtk_thermal.c | 9 ++++-----
>>>  1 file changed, 4 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/thermal/mtk_thermal.c b/drivers/thermal/mtk_thermal.c
>>> index 9eaca432920e..594ad4f0f8cd 100644
>>> --- a/drivers/thermal/mtk_thermal.c
>>> +++ b/drivers/thermal/mtk_thermal.c
>>> @@ -22,6 +22,7 @@
>>>  #include <linux/thermal.h>
>>>  #include <linux/reset.h>
>>>  #include <linux/types.h>
>>> +#include <linux/power/mtk_svs.h>
>>>  
>>>  /* AUXADC Registers */
>>>  #define AUXADC_CON1_SET_V	0x008
>>> @@ -262,7 +263,7 @@ struct mtk_thermal {
>>>  	struct clk *clk_peri_therm;
>>>  	struct clk *clk_auxadc;
>>>  	/* lock: for getting and putting banks */
>>> -	struct mutex lock;
>>> +	unsigned long flags;
>>>  
>>>  	/* Calibration values */
>>>  	s32 adc_ge;
>>> @@ -561,7 +562,7 @@ static void mtk_thermal_get_bank(struct mtk_thermal_bank *bank)
>>>  	u32 val;
>>>  
>>>  	if (mt->conf->need_switch_bank) {
>>> -		mutex_lock(&mt->lock);
>>> +		mt->flags = claim_mtk_svs_lock();
>>>  
>>>  		val = readl(mt->thermal_base + PTPCORESEL);
>>>  		val &= ~0xf;
>>> @@ -581,7 +582,7 @@ static void mtk_thermal_put_bank(struct mtk_thermal_bank *bank)
>>>  	struct mtk_thermal *mt = bank->mt;
>>>  
>>>  	if (mt->conf->need_switch_bank)
>>> -		mutex_unlock(&mt->lock);
>>> +		release_mtk_svs_lock(mt->flags);
>>>  }
>>>  
>>>  /**
>>> @@ -938,8 +939,6 @@ static int mtk_thermal_probe(struct platform_device *pdev)
>>>  	if (ret)
>>>  		return ret;
>>>  
>>> -	mutex_init(&mt->lock);
>>> -
>>>  	mt->dev = &pdev->dev;
>>>  
>>>  	auxadc = of_parse_phandle(np, "mediatek,auxadc", 0);
>>>
>>
>>
> 


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