linux-kernel - Re: [PATCH 2/4] cpufreq: qcom: Re-arrange register offsets to support per core L3 DCVS

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Date:   Wed, 4 Aug 2021 12:01:51 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Sibi Sankar <sibis@...eaurora.org>, bjorn.andersson@...aro.org,
        mka@...omium.org, robh+dt@...nel.org
Cc:     viresh.kumar@...aro.org, agross@...nel.org, rjw@...ysocki.net,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        dianders@...omium.org, tdas@...eaurora.org
Subject: Re: [PATCH 2/4] cpufreq: qcom: Re-arrange register offsets to support
 per core L3 DCVS

Quoting Sibi Sankar (2021-07-29 11:04:43)
> Qualcomm SoCs (starting with SM8350) support per core voting for L3 cache
> frequency.

And the L3 cache frequency voting code can't be put into this cpufreq
driver?

> So, re-arrange the cpufreq register offsets to allow access for
> the L3 interconnect to implement per core control. Also prevent binding
> breakage caused by register offset shuffling by using the SM8250/SM8350
> EPSS compatible.
>
> Fixes: 7dbd121a2c58 ("arm64: dts: qcom: sc7280: Add cpufreq hw node")
> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> ---
>  drivers/cpufreq/qcom-cpufreq-hw.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index f86859bf76f1..74ef3b38343b 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -28,6 +28,7 @@ struct qcom_cpufreq_soc_data {
>         u32 reg_volt_lut;
>         u32 reg_perf_state;
>         u8 lut_row_size;
> +       bool skip_enable;
>  };
>
>  struct qcom_cpufreq_data {
> @@ -257,19 +258,31 @@ static const struct qcom_cpufreq_soc_data qcom_soc_data = {
>         .reg_volt_lut = 0x114,
>         .reg_perf_state = 0x920,
>         .lut_row_size = 32,
> +       .skip_enable = false,
>  };
>
>  static const struct qcom_cpufreq_soc_data epss_soc_data = {
> +       .reg_freq_lut = 0x0,
> +       .reg_volt_lut = 0x100,
> +       .reg_perf_state = 0x220,
> +       .lut_row_size = 4,
> +       .skip_enable = true,
> +};
> +
> +static const struct qcom_cpufreq_soc_data epss_sm8250_soc_data = {
>         .reg_enable = 0x0,
>         .reg_freq_lut = 0x100,
>         .reg_volt_lut = 0x200,
>         .reg_perf_state = 0x320,
>         .lut_row_size = 4,
> +       .skip_enable = false,
>  };
>
>  static const struct of_device_id qcom_cpufreq_hw_match[] = {
>         { .compatible = "qcom,cpufreq-hw", .data = &qcom_soc_data },
>         { .compatible = "qcom,cpufreq-epss", .data = &epss_soc_data },
> +       { .compatible = "qcom,sm8250-cpufreq-epss", .data = &epss_sm8250_soc_data },
> +       { .compatible = "qcom,sm8350-cpufreq-epss", .data = &epss_sm8250_soc_data },
>         {}
>  };
>  MODULE_DEVICE_TABLE(of, qcom_cpufreq_hw_match);
> @@ -334,10 +347,12 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
>         data->res = res;
>
>         /* HW should be in enabled state to proceed */

It looks odd that we're no longer making sure that the clk domain is
enabled when we probe the driver. Why is that OK?

> -       if (!(readl_relaxed(base + data->soc_data->reg_enable) & 0x1)) {
> -               dev_err(dev, "Domain-%d cpufreq hardware not enabled\n", index);
> -               ret = -ENODEV;
> -               goto error;
> +       if (!data->soc_data->skip_enable) {
> +               if (!(readl_relaxed(base + data->soc_data->reg_enable) & 0x1)) {
> +                       dev_err(dev, "Domain-%d cpufreq hardware not enabled\n", index);
> +                       ret = -ENODEV;
> +                       goto error;
> +               }
>         }
>