linux-kernel - Re: [PATCH 1/3] thermal: hisilicon: add new hisilicon thermal sensor driver

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Date:	Mon, 23 Mar 2015 16:30:59 +0800
From:	kongxinwei <xweikong@...mail.com>
To:	Leo Yan <leo.yan@...aro.org>, Mark Rutland <mark.rutland@....com>
CC:	kongxinwei <kong.kongxinwei@...ilicon.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linuxarm@...wei.com" <linuxarm@...wei.com>,
	"xuwei5@...ilicon.com" <xuwei5@...ilicon.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"edubezval@...il.com" <edubezval@...il.com>,
	"rui.zhuang@...el.com" <rui.zhuang@...el.com>,
	"liguozhu@...ilicon.com" <liguozhu@...ilicon.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/3] thermal: hisilicon: add new hisilicon thermal sensor
 driver


On 03/23/2015 12:46 PM, Leo Yan wrote:
> On Fri, Mar 20, 2015 at 03:55:27PM +0000, Mark Rutland wrote:
>>>> That may be the case in the code as it stands today, but per the binding
>>>> the trip points are the temperatures at which an action is to be taken.
>>>>
>>>> The thermal-zone has poilling-delay and polling-delay-passive, but
>>>> there's no reason you couldn't also use the interrupt to handle the
>>>> "hot" trip-point, adn the reset at the "critical" trip-point. All that's
>>>> missing is the plumbing in order to do so.
>>>>
>>>> So please co-ordinate with the thermal framework to do that.
>>> Let's dig further more for this point, so that we can get more specific
>>> gudiance and have a good preparation for next version's patch set.
>>>
>>> After i reviewed the thermal framework code, currently have one smooth
>>> way to co-ordinate the trip points w/t thermal framework: use the function
>>> *thermal_zone_device_register()* to register sensor, and can use the
>>> callback function .get_trip_temp to tell thermal framework for the
>>> trip points' temperature.
>>>
>>> For hisi thermal case, now the driver is using the function
>>> *thermal_zone_of_sensor_register* to register sensor, but use this way
>>> i have not found there have standard APIs which can be used by sensor
>>> driver to get the trip points info from thermal framework.
>>>
>>> I may miss something for thermal framework, so if have existed APIs to
>>> get the trip points, could pls point out?
>> I am only familiar with the binding, not the Linux implementation -- The
>> latter can change to accomodate your hardware without requiring binding
>> changes. Please co-ordinate with the thermal maintainers.
> Found the functions of_thermal_get_trip_points(tz) and of_thermal_get_ntrips(tz)
> will help for this.
>
>>>>>>> +       if (of_property_read_bool(np, "hisilicon,tsensor-bind-irq")) {
>>>>>>> +
>>>>>>> +               if (data->irq_bind_sensor != -1)
>>>>>>> +                       dev_warn(&pdev->dev, "irq has bound to index %d\n",
>>>>>>> +                                data->irq_bind_sensor);
>>>>>>> +
>>>>>>> +               /* bind irq to this sensor */
>>>>>>> +               data->irq_bind_sensor = index;
>>>>>>> +       }
>>>>>> I don't see why this should be specified in the DT. Why do you believe
>>>>>> it should?
>>>>> The thermal sensor module has four sensors, but have only one
>>>>> interrupt signal; This interrupt can only be used by one sensor;
>>>>> So want to use dts to bind the interrupt with one selected sensor.
>>>> That's not all that great, though I'm not exactly sure how the kernel
>>>> would select the best sensor to measure with. It would be good if you
>>>> could talk to the thermal maintainers w.r.t. this.
>>> This will be decided by the silicon, right? Every soc has different
>>> combination with cpu/gpu/vpu, so which part is hottest, this maybe
>>> highly dependent on individual SoC.
>>>
>>> S/W just need provide the flexibility so that later can choose
>>> the interrupt to bind with the sensor within the hottest part.
>> Then the property you care about is which sensor is closest to what is
>> likely to be the hottest component. Given that, the kernel can decide
>> how to use the interrupt.
> Will modify the driver to dynamically bind the interrupt to hottest
> sensor; Appreciate for good suggestion.
>
> Thanks,
> Leo Yan

Hi mark:
    Thank you for your comments,please wait the next version to slove your
presenting problem.

Thanks.
Xinwei

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