linux-kernel - Re: [PATCH v6 5/5] arm64: dts: qcom: Update IPQ9574 xo_board

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Message-ID: <fb9d117e-77bd-4a01-a738-f72d07f6b84c@oss.qualcomm.com>
Date: Thu, 19 Dec 2024 22:28:17 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Jie Luo <quic_luoj@...cinc.com>,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, quic_kkumarcs@...cinc.com,
        quic_suruchia@...cinc.com, quic_pavir@...cinc.com,
        quic_linchen@...cinc.com, quic_leiwei@...cinc.com,
        bartosz.golaszewski@...aro.org, srinivas.kandagatla@...aro.org
Subject: Re: [PATCH v6 5/5] arm64: dts: qcom: Update IPQ9574 xo_board_clk to
 use fixed factor clock

On 18.12.2024 12:17 PM, Jie Luo wrote:
> 
> 
> On 12/13/2024 6:30 PM, Jie Luo wrote:
>>
>>
>> On 12/13/2024 2:33 AM, Konrad Dybcio wrote:
>>> On 7.11.2024 10:50 AM, Luo Jie wrote:
>>>> xo_board_clk is fixed to 24 MHZ, which is routed from WiFi output clock
>>>> 48 MHZ (also being the reference clock of CMN PLL) divided 2 by analog
>>>> block routing channel.
>>>>
>>>> Signed-off-by: Luo Jie <quic_luoj@...cinc.com>
>>>> ---
>>>>   arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi | 7 ++++++-
>>>>   arch/arm64/boot/dts/qcom/ipq9574.dtsi            | 3 ++-
>>>>   2 files changed, 8 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi b/arch/ arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
>>>> index 78f6a2e053d5..9a8692377176 100644
>>>> --- a/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/ipq9574-rdp-common.dtsi
>>>> @@ -174,8 +174,13 @@ &ref_48mhz_clk {
>>>>       clock-mult = <1>;
>>>>   };
>>>> +/*
>>>> + * The frequency of xo_board_clk is fixed to 24 MHZ, which is routed
>>>> + * from WiFi output clock 48 MHZ divided by 2.
>>>> + */
>>>>   &xo_board_clk {
>>>> -    clock-frequency = <24000000>;
>>>> +    clock-div = <2>;
>>>> +    clock-mult = <1>;
>>>>   };
>>>>   &xo_clk {
>>>> diff --git a/arch/arm64/boot/dts/qcom/ipq9574.dtsi b/arch/arm64/boot/ dts/qcom/ipq9574.dtsi
>>>> index 8246a00a3e3e..25aed33e9358 100644
>>>> --- a/arch/arm64/boot/dts/qcom/ipq9574.dtsi
>>>> +++ b/arch/arm64/boot/dts/qcom/ipq9574.dtsi
>>>> @@ -32,7 +32,8 @@ sleep_clk: sleep-clk {
>>>>           };
>>>>           xo_board_clk: xo-board-clk {
>>>> -            compatible = "fixed-clock";
>>>> +            compatible = "fixed-factor-clock";
>>>> +            clocks = <&ref_48mhz_clk>;
>>>
>>> This must be squashed with the previous patch, you can't introduce
>>> code and replace it immediately afterwards.
>>>
>>> Konrad
> 
> Hi Konrad,
> 
> Looking at this comment again, there may have been some
> misunderstanding. We are not introducing xo_board_clk in patch 4 of this
> series. xo_board_clk is a pre-existing node.
> 
> As part of this additional patch 5, we wanted to address Dmitry's
> comment earlier in v5 (reference to comment below), by converting the
> xo_board_clk as well to a fixed-factor clock. So it is better to keep
> this change as a separate patch in my view. Hope this is OK.

Oh okay..

What's the difference between xo_board_clk and xo_clk then, if the
divider is accounted for in xo_board_clk?

Konrad