linux-kernel - Re: [PATCH 1/7] dt-bindings: soc: qcom: Add qcom-pbs bindings

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Message-ID: <431faa87-d152-5f7a-40fd-8b6fe26f0bb9@linaro.org>
Date:   Tue, 11 Jul 2023 07:58:55 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Anjelique Melendez <quic_amelende@...cinc.com>,
        Rob Herring <robh@...nel.org>
Cc:     pavel@....cz, lee@...nel.org, thierry.reding@...il.com,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        u.kleine-koenig@...gutronix.de, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-pwm@...r.kernel.org
Subject: Re: [PATCH 1/7] dt-bindings: soc: qcom: Add qcom-pbs bindings

On 11/07/2023 05:52, Anjelique Melendez wrote:
> 
> 
> On 7/1/2023 4:03 AM, Krzysztof Kozlowski wrote:
>> On 29/06/2023 03:19, Anjelique Melendez wrote:
>>
>>>>> +examples:
>>>>> +  - |
>>>>> +    pmic {
>>>>> +      #address-cells = <1>;
>>>>> +      #size-cells = <0>;
>>>>> +
>>>>> +      qcom,pbs@...0 {
>>>>> +        compatible = "qcom,pbs";
>>>>> +        reg = <0x7400>;
>>>>> +      };
>>>>
>>>> Why do you need a child node for this? Is there more than 1 instance in 
>>>> a PMIC? Every sub-function of a PMIC doesn't have to have a DT node.
>>>>
>>>
>>> We currently have another downstream driver (which is planned to get upstreamed)
>>> which also needs a handle to a pbs device in order to properly trigger events. 
>>
>> I don't see how does it answer Rob's concerns. Neither mine about
>> incomplete binding. You don't need pbs node here for that.
>>
>> Anyway, whatever you have downstream also does not justify any changes.
>> Either upstream these so we can see it or drop this binding.
>>
>> Best regards,
>> Krzysztof
>>
> 
> On PMI632, peripherals are partitioned over 2 different SIDs
> (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/qcom/pmi632.dtsi?h=v6.5-rc1#n42
> and https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/qcom/pmi632.dtsi?h=v6.5-rc1#n149).
> Unfortunately, the pbs peripheral and the lpg peripherals are on different
> PMI632 devices and therefore have different regmaps.
>  
> If we get rid of the pbs node we need to get a handle to the proper regmap.
> I see two possible options, we could either introduce a new client property
> which points to a peripheral on the same device as pbs.
> 
> i.e.
> 	led-controller {
> 		compatible = "qcom,pmi632-lpg";
>       		#address-cells = <1>;
>       		#size-cells = <0>;
>       		#pwm-cells = <2>;
>      		nvmem-names = "lpg_chan_sdam";
>       		nvmem = <&pmi632_sdam7>;
>       		qcom,pbs-phandle = <&pmi632_gpios>;
>       		..... 
> 	};
> Then when client is probing could do something like the following to get the regmap
> 
> 	dn = of_parse_phandle(node, "qcom,pbs-phandle", 0);
> 	pdev = of_find_device_by_node(dn);
> 	pbs_regmap = dev_get_regmap(&pdev->dev->parent, NULL);
> 
> 
> 
> Or we could use the nvmem phandle and just have something like this in client's probe
> 
> 	dn = of_parse_phandle(node, "nvmem", 0);
> 	pdev = of_find_device_by_node(dn);
> 	pbs_regmap = dev_get_regmap(&pdev->dev->parent, NULL);
> 
> 
> 
> Let me know what your thoughts are on this.

Rob asked you - "Is there more than 1 instance in a PMIC?" - and you did
not answer positively, just mentioned something about drivers in
downstream, which do not matter. So is the answer for that question:
yes, you have two instances of the same PMIC differing by presence of
PBS and other features"?

Best regards,
Krzysztof