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From:   Srinath Mannam <srinath.mannam@broadcom.com>
Date:   Fri, 13 Jul 2018 08:33:50 +0530
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Subject: Re: [PATCH v2 1/3] dt-bindings: thermal: Add binding document for SR thermal
To:     Rob Herring <robh@kernel.org>
Cc:     Zhang Rui <rui.zhang@intel.com>,
        Eduardo Valentin <edubezval@gmail.com>,
        Mark Rutland <mark.rutland@arm.com>,
        devicetree@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
        Pramod Kumar <pramod.kumar@broadcom.com>,
        Vikram Prakash <vikram.prakash@broadcom.com>,
        Ray Jui <ray.jui@broadcom.com>
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Hi Rob,

I have provided my inputs for the purpose of having multiple nodes.
Please get back if you have any comments or suggestions.

Regards,
Srinath.

On Tue, Jul 3, 2018 at 4:15 PM, Srinath Mannam
<srinath.mannam@broadcom.com> wrote:
> Hi Rob,
>
> Kindly provide your feedback.
>
> Regards,
> Srinath.
>
> On Fri, Jun 22, 2018 at 11:21 AM, Srinath Mannam
> <srinath.mannam@broadcom.com> wrote:
>> Hi Rob,
>>
>> Please find my comments for the reason to have multiple DT nodes.
>>
>> On Thu, Jun 21, 2018 at 1:22 AM, Rob Herring <robh@kernel.org> wrote:
>>> On Mon, Jun 18, 2018 at 02:01:17PM +0530, Srinath Mannam wrote:
>>>> From: Pramod Kumar <pramod.kumar@broadcom.com>
>>>>
>>>> Add binding document for supported thermal implementation
>>>> in Stingray.
>>>>
>>>> Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
>>>> Reviewed-by: Ray Jui <ray.jui@broadcom.com>
>>>> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
>>>> Reviewed-by: Srinath Mannam <srinath.mannam@broadcom.com>
>>>> ---
>>>>  .../bindings/thermal/brcm,sr-thermal.txt           | 45 ++++++++++++++++++++++
>>>>  1 file changed, 45 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/thermal/brcm,sr-thermal.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/thermal/brcm,sr-thermal.txt b/Documentation/devicetree/bindings/thermal/brcm,sr-thermal.txt
>>>> new file mode 100644
>>>> index 0000000..33f9e11
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/thermal/brcm,sr-thermal.txt
>>>> @@ -0,0 +1,45 @@
>>>> +* Broadcom Stingray Thermal
>>>> +
>>>> +This binding describes thermal sensors that is part of Stingray SoCs.
>>>> +
>>>> +Required properties:
>>>> +- compatible : Must be "brcm,sr-thermal"
>>>> +- reg : memory where tmon data will be available.
>>>> +
>>>> +Example:
>>>> +     tmons {
>>>> +             compatible = "simple-bus";
>>>> +             #address-cells = <1>;
>>>> +             #size-cells = <1>;
>>>> +             ranges;
>>>> +
>>>> +             tmon_ihost0: thermal@8f100000 {
>>>> +                     compatible = "brcm,sr-thermal";
>>>> +                     reg = <0x8f100000 0x4>;
>>>> +             };
>>>
>>> You still haven't given me a compelling reason why you need a node per
>>> register.
>>>
>>> You have a single range of registers. Make this 1 node.
>>>
>>
>> We Have two reasons to have multiple nodes..
>> 1. Our chip has multiple functional blocks. Each functional block has
>> its own thermal zone.
>> Functional blocks and their thermal zones enabled/disabled based on end product.
>> Few functional blocks need to disabled for few products so thermal
>> zones also need to disable.
>> In that case, nodes of specific thermal zones are removed from DTS
>> file of corresponding product.
>>
>> 2. Thermal framework provides sysfs interface to configure thermal
>> zones and read temperature of thermal zone.
>> To configure individual thermal zone, we need to have separate DT node.
>> Same to read temperature of individual thermal zone.
>> Ex: To read temperature of thermal zone 0.
>>          cat /sys/class/thermal/thermal_zone0/temp
>>      To configure trip temperature of thermal zone 0.
>>           echo 110000 > /sys/class/thermal/thermal_zone0/trip_point_0_temp
>>
>> Also to avoid driver source change for the multiple products it is
>> clean to have multiple DT nodes.
>>
>>> Rob