Message-ID: <9d22a81c-f7f3-e4c0-e6e5-e07f2d8d89f8@nvidia.com>
Date:   Fri, 23 Nov 2018 16:28:02 +0800
From:   Wei Ni <wni@...dia.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        <thierry.reding@...il.com>, <linux-tegra@...r.kernel.org>
CC:     <rui.zhang@...el.com>, <edubezval@...il.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] thermal: tegra: continue if sensor register fails



On 23/11/2018 2:51 PM, Daniel Lezcano wrote:
> 
> Hi wei,
> 
> On 23/11/2018 07:15, Wei Ni wrote:
>>
>>
>> On 22/11/2018 9:07 PM, Daniel Lezcano wrote:
>>> On 22/11/2018 08:10, Wei Ni wrote:
>>>>
>>>>
>>>> On 21/11/2018 8:51 PM, Daniel Lezcano wrote:
>>>>> On 21/11/2018 11:23, Wei Ni wrote:
>>>>>>
>>>>>>
>>>>>> On 21/11/2018 4:55 PM, Daniel Lezcano wrote:
>>>>>>> On 13/11/2018 11:06, Wei Ni wrote:
>>>>>>>> Don't bail when a sensor fails to register with the
>>>>>>>> thermal zone and allow other sensors to register.
>>>>>>>> This allows other sensors to register with thermal
>>>>>>>> framework even if one sensor fails registration.
>>>>>>>
>>>>>>> I'm not sure if ignoring the error is really safe. Can you describe the
>>>>>>> real situation you want to overcome ? How do you differentiate critical
>>>>>>> sensors ?
>>>>>>
>>>>>> The driver will always try to register 4 thermal zones, including cpu,
>>>>>> gpu, mem and pll, but if the dts file doesn't set the corresponding
>>>>>> sensors, then the register will be failed.
>>>>>> Normally, the dts file will set all 4 sensors, but there may have some
>>>>>> platform doesn't support them all. So we post this patch.
>>>>>
>>>>> Ignoring errors is not the way to go to support different platforms. Fix
>>>>> the DT.
>>>>
>>>> The issue isn't in DT file. The Tegra soc thermal include 4 sensors:
>>>> cpu, gpu, mem, pll. But in some platforms, for example, we may only need
>>>> to support 2 sensors, such as cpu and gpu, so we only configure these
>>>> two senors in DT file. But the driver will always try to register 4
>>>> sensors, cpu/gpu/mem/pll, so mem and pll will be registered failed. So
>>>> in this case we need to ignoring the failure, and continue to enable the
>>>> driver.
>>>
>>> You can fix this by changing the driver to support the platform and
>>> register the sensor you are interested in.
>>>
>>> Ignoring errors is not a good idea.
>>
>> If hit the errors, the driver will print out the warning. In current
>> code, the driver probe routine will return failure directly, indeed it
>> didn't do anything either except print out warnings.
>> I think this error should not block other sensors' registration. Let's
>> consider this case, we have four sensors, if the one sensor register
>> failed, then the driver return probe failure, so the drive will not be
>> enabled, and other sensor can't work either, it mean the device may boot
>> up without any thermal sensors.
>> Or if the error is the -ENODEV, that mean the we didn't set
>> corresponding sensor id in the dt file, so we can continue to register.
>> If the error is other value, then we can return directly.
> 
> It is a possibility but may be there are a couple of alternatives:
> 
> 1. If there is a compatible string for the platform variant, use it to
> probe the right sensors
> 
> or
> 
> 2. Use the qoriq driver approach by reparsing the DT and find out the
> thermal zone and their respective sensor id.

Daniel, thanks for your comments, will consider it in my next version.

Wei.
> 
> 
>>>>>> BTW, what do you mean "critical sensors"? We will set critical trip temp
>>>>>> for all sensors.
>>>>>
>>>>> I meant sensor for thermal zone getting really high temperature.
>>>>
>>>> We doesn't have the critical sensors. We set the critical trip temp for
>>>> all registered sensors. And these trip temp is set to the Tegra
>>>> hardware. So it mean if the temperature reached the critical trip point,
>>>> then the system will be shutdown directly.
>>>>
>>>>>
>>>>>
>>>>>>>> Signed-off-by: Wei Ni <wni@...dia.com>
>>>>>>>> ---
>>>>>>>>  drivers/thermal/tegra/soctherm.c | 8 +++++---
>>>>>>>>  1 file changed, 5 insertions(+), 3 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/thermal/tegra/soctherm.c b/drivers/thermal/tegra/soctherm.c
>>>>>>>> index ed28110a3535..a824d2e63af3 100644
>>>>>>>> --- a/drivers/thermal/tegra/soctherm.c
>>>>>>>> +++ b/drivers/thermal/tegra/soctherm.c
>>>>>>>> @@ -1370,9 +1370,9 @@ static int tegra_soctherm_probe(struct platform_device *pdev)
>>>>>>>>  							 &tegra_of_thermal_ops);
>>>>>>>>  		if (IS_ERR(z)) {
>>>>>>>>  			err = PTR_ERR(z);
>>>>>>>> -			dev_err(&pdev->dev, "failed to register sensor: %d\n",
>>>>>>>> -				err);
>>>>>>>> -			goto disable_clocks;
>>>>>>>> +			dev_warn(&pdev->dev, "failed to register sensor %s: %d\n",
>>>>>>>> +				 soc->ttgs[i]->name, err);
>>>>>>>> +			continue;
>>>>>>>>  		}
>>>>>>>>  
>>>>>>>>  		zone->tz = z;
>>>>>>>> @@ -1434,6 +1434,8 @@ static int __maybe_unused soctherm_resume(struct device *dev)
>>>>>>>>  		struct thermal_zone_device *tz;
>>>>>>>>  
>>>>>>>>  		tz = tegra->thermctl_tzs[soc->ttgs[i]->id];
>>>>>>>> +		if (!tz)
>>>>>>>> +			continue;
>>>>>>>>  		err = tegra_soctherm_set_hwtrips(dev, soc->ttgs[i], tz);
>>>>>>>>  		if (err) {
>>>>>>>>  			dev_err(&pdev->dev,
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>
>>>>>
>>>
>>>
> 
> 

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