linux-kernel - Re: [PATCH v5 1/4] clk: zynqmp: Use firmware specific common clock flags

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Date:   Fri, 25 Jun 2021 16:21:43 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Rajan Vaja <rajan.vaja@...inx.com>, kristo@...nel.org,
        lee.jones@...aro.org, michal.simek@...inx.com,
        mturquette@...libre.com, quanyang.wang@...driver.com
Cc:     linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Rajan Vaja <rajan.vaja@...inx.com>
Subject: Re: [PATCH v5 1/4] clk: zynqmp: Use firmware specific common clock flags

Quoting Rajan Vaja (2021-06-24 05:16:30)
> diff --git a/drivers/clk/zynqmp/clkc.c b/drivers/clk/zynqmp/clkc.c
> index db8d0d7161ce..af06a195ec46 100644
> --- a/drivers/clk/zynqmp/clkc.c
> +++ b/drivers/clk/zynqmp/clkc.c
> @@ -271,6 +271,34 @@ static int zynqmp_pm_clock_get_topology(u32 clock_id, u32 index,
>         return ret;
>  }
>  
> +unsigned long zynqmp_clk_map_common_ccf_flags(const u32 zynqmp_flag)
> +{
> +       unsigned long ccf_flag = 0;
> +
> +       if (zynqmp_flag & ZYNQMP_CLK_SET_RATE_GATE)
> +               ccf_flag |= CLK_SET_RATE_GATE;
> +       if (zynqmp_flag & ZYNQMP_CLK_SET_PARENT_GATE)
> +               ccf_flag |= CLK_SET_PARENT_GATE;
> +       if (zynqmp_flag & ZYNQMP_CLK_SET_RATE_PARENT)
> +               ccf_flag |= CLK_SET_RATE_PARENT;
> +       if (zynqmp_flag & ZYNQMP_CLK_IGNORE_UNUSED)
> +               ccf_flag |= CLK_IGNORE_UNUSED;
> +       if (zynqmp_flag & ZYNQMP_CLK_GET_RATE_NOCACHE)
> +               ccf_flag |= CLK_GET_RATE_NOCACHE;

Does the firmware really use all these flags? Ideally we get rid of the
above two.

> +       if (zynqmp_flag & ZYNQMP_CLK_SET_RATE_NO_REPARENT)
> +               ccf_flag |= CLK_SET_RATE_NO_REPARENT;
> +       if (zynqmp_flag & ZYNQMP_CLK_GET_ACCURACY_NOCACHE)
> +               ccf_flag |= CLK_GET_ACCURACY_NOCACHE;
> +       if (zynqmp_flag & ZYNQMP_CLK_RECALC_NEW_RATES)
> +               ccf_flag |= CLK_RECALC_NEW_RATES;

And this one.

> +       if (zynqmp_flag & ZYNQMP_CLK_SET_RATE_UNGATE)
> +               ccf_flag |= CLK_SET_RATE_UNGATE;
> +       if (zynqmp_flag & ZYNQMP_CLK_IS_CRITICAL)
> +               ccf_flag |= CLK_IS_CRITICAL;

And this one.

I worry that supporting all these flags will mean we can never get rid
of them. And we currently don't support setting critical via DT, which
is essentially another firmware interface like this one.

> +
> +       return ccf_flag;
> +}
> +
>  /**
>   * zynqmp_clk_register_fixed_factor() - Register fixed factor with the
>   *                                     clock framework