linux-kernel - Re: [PATCH 2/7] clk: qcom: Add Global Clock Controller driver for IPQ9574

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Message-ID: <7bf1444d-7f57-0ddd-2466-95d396cc92e0@quicinc.com>
Date:   Tue, 24 Jan 2023 19:20:20 +0530
From:   Devi Priya <quic_devipriy@...cinc.com>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>, <agross@...nel.org>,
        <andersson@...nel.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <mturquette@...libre.com>,
        <sboyd@...nel.org>, <linus.walleij@...aro.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <p.zabel@...gutronix.de>, <shawnguo@...nel.org>, <arnd@...db.de>,
        <marcel.ziswiler@...adex.com>, <dmitry.baryshkov@...aro.org>,
        <nfraprado@...labora.com>, <broonie@...nel.org>,
        <tdas@...eaurora.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <linux-gpio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     <quic_srichara@...cinc.com>, <quic_gokulsri@...cinc.com>,
        <quic_sjaganat@...cinc.com>, <quic_kathirav@...cinc.com>,
        <quic_arajkuma@...cinc.com>, <quic_anusha@...cinc.com>,
        <quic_poovendh@...cinc.com>
Subject: Re: [PATCH 2/7] clk: qcom: Add Global Clock Controller driver for
 IPQ9574



On 1/24/2023 3:23 PM, Konrad Dybcio wrote:
> 
> 
> On 24.01.2023 08:27, Devi Priya wrote:
>>
>>
>> On 1/13/2023 7:39 PM, Konrad Dybcio wrote:
>>>
>>>
>>> On 13.01.2023 14:21, Devi Priya wrote:
>>>>
>>>>
>>>> On 1/10/2023 6:07 PM, Konrad Dybcio wrote:
>>>>>
>>>>>
>>>>> On 10.01.2023 13:13, devi priya wrote:
>>>>>> Add Global Clock Controller (GCC) driver for ipq9574 based devices
>>>>>>
>>>>>> Co-developed-by: Anusha Rao <quic_anusha@...cinc.com>
>>>>>> Signed-off-by: Anusha Rao <quic_anusha@...cinc.com>
>>>>>> Signed-off-by: devi priya <quic_devipriy@...cinc.com>
>>>>>> ---
>>> [...]
>>>
>>>>>> +static struct clk_branch gcc_blsp1_qup6_i2c_apps_clk = {
>>>>>> +    .halt_reg = 0x07024,
>>>>>> +    .clkr = {
>>>>>> +        .enable_reg = 0x07024,
>>>>>> +        .enable_mask = BIT(0),
>>>>>> +        .hw.init = &(struct clk_init_data) {
>>>>>> +            .name = "gcc_blsp1_qup6_i2c_apps_clk",
>>>>>> +            .parent_hws = (const struct clk_hw *[]) {
>>>>>> +                    &blsp1_qup6_i2c_apps_clk_src.clkr.hw },
>>>>>> +            .num_parents = 1,
>>>>>> +            .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED,
>>>>> Sounds very much like a hack..
>>>> Got it, will remove the clock entry as it is not being used in linux
>>> I'm not sure removing it is the best option, somebody might have a
>>> funky board where they use this particular QUP for I2C for whatever
>>> reason and then the clock would have to be re-added..
>> Sure, Understood
>> This clock is used by the RPM component to communicate with PMIC and we
>> would add the critical flag here
> Okay, so this SoC is intended to ship with some RPM PMICs and
> *always* with an I2C companion that's required for some basic
> functionality, correct?
> 
> Otherwise, if it's just for wifi/multimedia/etc (like PM8008ij
> on some newer devices), you should not make it critical and
> simply rely on Linux keeping it alive like so:
> 
> consumer takes a regulator
> the regulator does not go to sleep because it's consumed
> the PMIC is active because a regulator on it is being used
> the I2C bus is active because its child PMIC is used
> the I2C clocks are alive because there's an active user
> 
Yes correct, the SoC would always have an I2C companion
> Konrad
>>
>>> Thanks for addressing all of the review comments so thoroughly!
>>>
>>> Konrad
>>
>> Best Regards,
>> Devi Priya