linux-kernel - Re: [PATCH V2 3/6] clk: qcom: clk-alpha-pll: Remove explicit CAL

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Message-ID: <7074f718-a3d5-8a03-3830-77a5a0b15500@linaro.org>
Date:   Fri, 26 May 2023 18:53:46 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Jagadeesh Kona <quic_jkona@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     Bjorn Andersson <andersson@...nel.org>,
        Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
        Vinod Koul <vkoul@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Taniya Das <quic_tdas@...cinc.com>,
        Satya Priya Kakitapalli <quic_skakitap@...cinc.com>,
        Imran Shaik <quic_imrashai@...cinc.com>,
        Ajit Pandey <quic_ajipan@...cinc.com>
Subject: Re: [PATCH V2 3/6] clk: qcom: clk-alpha-pll: Remove explicit CAL_L
 configuration for EVO PLL

On 26/05/2023 12:33, Konrad Dybcio wrote:
> 
> 
> On 25.05.2023 19:21, Jagadeesh Kona wrote:
>> In lucid evo pll, the CAL_L field is part of L value register itself, and
>> the l value configuration passed from clock controller driver includes
>> CAL_L and L values as well. Hence remove explicit configuration of CAL_L
>> for evo pll.
>>
>> Fixes: 260e36606a03 ("clk: qcom: clk-alpha-pll: add Lucid EVO PLL configuration interfaces")
>> Signed-off-by: Taniya Das <quic_tdas@...cinc.com>
>> Signed-off-by: Jagadeesh Kona <quic_jkona@...cinc.com>
>> ---
> Oh that isn't obvious at first sight, nice find!
> 
> I'd suggest a different solution though:
> 
> #define LUCID_EVO_PLL_L_LVAL	GENMASK(..
> #define LUCID_EVO_PLL_L_CAL_L	GENMASK(..
> 
> lval = FIELD_PREP(LUCID_EVO_PLL_L_LVAL, config->l) |
>         FIELD_PREP(LUCID_EVO_PLL_L_CAL_L, config->cal_l);
> 
> This would make the separation between the two parts more explicit
> 
> however
> 
> config->l would then represent the L value and not the end value
> written to the L register

Yes. I think there should be separate config->l and config->cal_l values 
(and probably ringosc_cal_l, basing on the comment in the source).

Just a question: is camcc-sm8550 using the same PLL type or is it some 
kind of subtype of lucid_evo PLL?

-- 
With best wishes
Dmitry