linux-kernel - Re: [PATCH] cpufreq: qoriq: enhance bus frequency calculation

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Message-ID: <20170309093917.GB3341@vireshk-i7>
Date:   Thu, 9 Mar 2017 15:09:17 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     YuanTian Tang <andy.tang@....com>
Cc:     rjw@...ysocki.net, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Tang Yuantian <Yuantian.Tang@....com>
Subject: Re: [PATCH] cpufreq: qoriq: enhance bus frequency calculation

On 09-03-17, 16:15, YuanTian Tang wrote:
> From: Tang Yuantian <Yuantian.Tang@....com>
> 
> On some platforms, property device-type may be missed in soc node
> in dts which caused the bus-frequency can not be obtained correctly.
> 
> This patch enhanced the bus-frequency calculation. When property
> device-type is missed in dts, bus-frequency will be obtained by
> looking up clock table to get platform clock and hence get its
> frequency.
> 
> Signed-off-by: Tang Yuantian <yuantian.tang@....com>
> ---
>  drivers/cpufreq/qoriq-cpufreq.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/cpufreq/qoriq-cpufreq.c b/drivers/cpufreq/qoriq-cpufreq.c
> index bfec1bc..0f22e40 100644
> --- a/drivers/cpufreq/qoriq-cpufreq.c
> +++ b/drivers/cpufreq/qoriq-cpufreq.c
> @@ -52,17 +52,27 @@ static u32 get_bus_freq(void)
>  {
>  	struct device_node *soc;
>  	u32 sysfreq;
> +	struct clk *pltclk;
> +	int ret;
>  
> +	/* get platform freq by searching bus-frequency property */
>  	soc = of_find_node_by_type(NULL, "soc");
> -	if (!soc)
> -		return 0;
> -
> -	if (of_property_read_u32(soc, "bus-frequency", &sysfreq))
> -		sysfreq = 0;
> +	if (soc) {
> +		ret = of_property_read_u32(soc, "bus-frequency", &sysfreq);
> +		of_node_put(soc);
> +		if (!ret)
> +			return sysfreq;
> +	}
>  
> -	of_node_put(soc);
> +	/* get platform freq by its clock name */
> +	pltclk = clk_get(NULL, "cg-pll0-div1");

Will this always work? If yes, then what about dropping the code parsing DT
completely ? That is, just rely on clk_get_rate() in all cases.

> +	if (IS_ERR(pltclk)) {
> +		pr_err("%s: can't get bus frequency %ld\n",
> +		__func__, PTR_ERR(pltclk));

You need to properly align this. Try running checkpatch over this patch or:

checkpatch --strict

> +		return PTR_ERR(pltclk);
> +	}
>  
> -	return sysfreq;
> +	return clk_get_rate(pltclk);
>  }
>  
>  static struct clk *cpu_to_clk(int cpu)
> -- 
> 2.1.0.27.g96db324

-- 
viresh