linux-kernel - Re: [PATCH v5 2/2] cpufreq: airoha: Add EN7581 CPUFreq SMCCC driver

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Message-ID: <20241204053211.6gdogcpi4g3eavw5@vireshk-i7>
Date: Wed, 4 Dec 2024 11:02:11 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Christian Marangi <ansuelsmth@...il.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-pm@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	upstream@...oha.com
Subject: Re: [PATCH v5 2/2] cpufreq: airoha: Add EN7581 CPUFreq SMCCC driver

On 03-12-24, 17:31, Christian Marangi wrote:
> diff --git a/drivers/cpufreq/airoha-cpufreq.c b/drivers/cpufreq/airoha-cpufreq.c
> +struct airoha_cpufreq_priv {
> +	struct clk_hw hw;
> +	struct generic_pm_domain pd;
> +
> +	int opp_token;
> +	struct dev_pm_domain_list *pd_list;
> +	struct platform_device *cpufreq_dt;
> +};
> +
> +static long airoha_cpufreq_clk_round(struct clk_hw *hw, unsigned long rate,
> +				     unsigned long *parent_rate)
> +{
> +	return rate;
> +}
> +
> +static unsigned long airoha_cpufreq_clk_get(struct clk_hw *hw,
> +					    unsigned long parent_rate)
> +{
> +	const struct arm_smccc_1_2_regs args = {
> +		.a0 = AIROHA_SIP_AVS_HANDLE,
> +		.a1 = AIROHA_AVS_OP_GET_FREQ,
> +	};
> +	struct arm_smccc_1_2_regs res;
> +
> +	arm_smccc_1_2_smc(&args, &res);
> +
> +	/* SMCCC returns freq in MHz */
> +	return (int)(res.a0 * 1000 * 1000);

Why casting to "int" when we can return ulong ?

> +}
> +
> +/* Airoha CPU clk SMCC is always enabled */
> +static int airoha_cpufreq_clk_is_enabled(struct clk_hw *hw)
> +{
> +	return true;
> +}
> +
> +static const struct clk_ops airoha_cpufreq_clk_ops = {
> +	.recalc_rate = airoha_cpufreq_clk_get,
> +	.is_enabled = airoha_cpufreq_clk_is_enabled,
> +	.round_rate = airoha_cpufreq_clk_round,
> +};
> +
> +static const char * const airoha_cpufreq_clk_names[] = { "cpu", NULL };
> +
> +/* NOP function to disable OPP from setting clock */
> +static int airoha_cpufreq_config_clks_nop(struct device *dev,
> +					  struct opp_table *opp_table,
> +					  struct dev_pm_opp *opp,
> +					  void *data, bool scaling_down)
> +{
> +	return 0;
> +}

I wonder whats better here. Provide this helper or provide a dummy clk-set-rate
at the provider itself ?

-- 
viresh