linux-kernel - Re: [PATCH v12] thermal: drivers: mediatek: Add the Low Voltage Thermal Sensor driver

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Message-ID: <ea30d169-2ae6-2744-fbfd-01bbbba36554@linaro.org>
Date:   Mon, 6 Feb 2023 15:38:15 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     bchihi@...libre.com, angelogioacchino.delregno@...labora.com,
        rafael@...nel.org, amitk@...nel.org, rui.zhang@...el.com,
        matthias.bgg@...il.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, rdunlap@...radead.org,
        ye.xingchen@....com.cn, p.zabel@...gutronix.de,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        khilman@...libre.com, james.lo@...iatek.com,
        rex-bc.chen@...iatek.com
Subject: Re: [PATCH v12] thermal: drivers: mediatek: Add the Low Voltage
 Thermal Sensor driver

On 06/02/2023 15:30, Krzysztof Kozlowski wrote:
> On 06/02/2023 15:07, Daniel Lezcano wrote:
>> On Wed, Feb 01, 2023 at 08:55:07AM +0100, Krzysztof Kozlowski wrote:
>>> On 31/01/2023 16:38, bchihi@...libre.com wrote:
>>>> From: Balsam CHIHI <bchihi@...libre.com>
>>>>
>>>> The Low Voltage Thermal Sensor (LVTS) is a multiple sensors, multi
>>>> controllers contained in a thermal domain.
>>>>
>>>> A thermal domains can be the MCU or the AP.
>>>>
>>>> Each thermal domains contain up to seven controllers, each thermal
>>>> controller handle up to four thermal sensors.
>>>>
>>>> The LVTS has two Finite State Machines (FSM), one to handle the
>>>> functionin temperatures range like hot or cold temperature and another
>>>> one to handle monitoring trip point. The FSM notifies via interrupts
>>>> when a trip point is crossed.
>>>>
>>>
>>> (...)
>>>
>>>> +
>>>> +struct lvts_domain {
>>>> +	struct lvts_ctrl *lvts_ctrl;
>>>> +	struct reset_control *reset;
>>>> +	struct clk *clk;
>>>> +	int num_lvts_ctrl;
>>>> +	void __iomem *base;
>>>> +	size_t calib_len;
>>>> +	u8 *calib;
>>>> +};
>>>> +
>>>> +#ifdef CONFIG_MTK_LVTS_THERMAL_DEBUGFS
>>>> +
>>>> +static struct dentry *root;
>>>
>>> How do you handle two instances of driver?
>>
>> For now, we can put the entry in /sys/kernel/debug/<dev_name>
>>
>> I'm preparing a debugfs series for the thermal framework and that will provide
>> an entry to hook in for the sensors debugfs if available
> 
> The code looked like it does not support it at all. I think it would
> remove entries from second instance, while unbinding the first (or the
> opposite).

Yes, and you are right.

So instead of having:

/sys/kernel/debugfs/lvts/lvts@mcu

We will have:

/sys/kernel/debugfs/lvts@mcu

Later, when the other domain is added, we will have:

/sys/kernel/debugfs/lvts@mcu
/sys/kernel/debugfs/lvts@ap

Each instance takes care of removing its own entry

When I'll introduce thermal debugfs, I'll take care of massaging the 
driver to have them like:

/sys/kernel/debugfs/thermal/thermal_zone/0/sensors/lvts@mcu,0
/sys/kernel/debugfs/thermal/thermal_zone/1/sensors/lvts@ap,1




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