linux-kernel - Re: [PATCH v2 4/5] clk: qcom: camcc-sc8280xp: Add sc8280xp CAMCC

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Date:   Sat, 30 Sep 2023 23:53:29 +0100
From:   Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        andersson@...nel.org, agross@...nel.org, mturquette@...libre.com,
        sboyd@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        jonathan@...ek.ca, quic_tdas@...cinc.com,
        vladimir.zapolskiy@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/5] clk: qcom: camcc-sc8280xp: Add sc8280xp CAMCC

On 30/09/2023 17:39, Konrad Dybcio wrote:
> 
>> +static struct clk_branch camcc_gdsc_clk = {
>> +    .halt_reg = 0xc1e4,
>> +    .halt_check = BRANCH_HALT,
>> +    .clkr = {
>> +        .enable_reg = 0xc1e4,
>> +        .enable_mask = BIT(0),
>> +        .hw.init = &(struct clk_init_data){
>> +            .name = "camcc_gdsc_clk",
>> +            .parent_hws = (const struct clk_hw*[]){
>> +                &camcc_xo_clk_src.clkr.hw,
>> +            },
>> +            .num_parents = 1,
>> +            .flags = CLK_IS_CRITICAL | CLK_SET_RATE_PARENT,
> "meh"
> 
> Is this clock only necessary for the GDSC to turn on?

Most of this code is autogenerated in downstream as I understand it a 
script is run against some definition the RTL one would hope.

I think that is probably how the gdsc clocks for the camcc are marked 
like this upstream already too.

grep CRITICAL drivers/clk/qcom/*camcc*
drivers/clk/qcom/camcc-sc7280.c:			.flags = CLK_IS_CRITICAL | 
CLK_SET_RATE_PARENT,
drivers/clk/qcom/camcc-sm8250.c:			.flags = CLK_IS_CRITICAL | 
CLK_SET_RATE_PARENT,
drivers/clk/qcom/camcc-sm8450.c:			.flags = CLK_IS_CRITICAL | 
CLK_SET_RATE_PARENT,

I can tell you what clocks this clock but I can't tell you where that 
clock routes too, so the best/only source of information I have is the 
flag that comes from the autogenerated downstream code.

I think the safe thing to do is to leave the flag as is TBH.

---
bod