Re: [PATCH v2 1/2] ARM: topology: Use a clock if possible to get the CPU frequency

[Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>]

On Mon, Jun 30, 2014 at 12:12:22PM +0200, Maxime Ripard wrote:
> The Cortex-A7 and Cortex-A15 based SoCs need a clock-frequency property in the
> topology code.
> 
> Allow to use a clock to provide the same information.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>

This looks fine to me, but I don't know this code.  Maybe Vincent Guittot
should be on the To: list (added)?

> ---
>  arch/arm/kernel/topology.c | 25 ++++++++++++++++++-------
>  1 file changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
> index 9d853189028b..268443d88094 100644
> --- a/arch/arm/kernel/topology.c
> +++ b/arch/arm/kernel/topology.c
> @@ -11,6 +11,7 @@
>   * for more details.
>   */
>  
> +#include <linux/clk.h>
>  #include <linux/cpu.h>
>  #include <linux/cpumask.h>
>  #include <linux/export.h>
> @@ -100,8 +101,8 @@ static void __init parse_dt_topology(void)
>  				 GFP_NOWAIT);
>  
>  	for_each_possible_cpu(cpu) {
> -		const u32 *rate;
> -		int len;
> +		struct clk *clk;
> +		u32 rate = 0;
>  
>  		/* too early to use cpu->of_node */
>  		cn = of_get_cpu_node(cpu, NULL);
> @@ -117,14 +118,24 @@ static void __init parse_dt_topology(void)
>  		if (cpu_eff->compatible == NULL)
>  			continue;
>  
> -		rate = of_get_property(cn, "clock-frequency", &len);
> -		if (!rate || len != 4) {
> -			pr_err("%s missing clock-frequency property\n",
> -				cn->full_name);
> +		clk = of_clk_get(cn, 0);
> +		if (!IS_ERR(clk))
> +			rate = clk_get_rate(clk);
> +		else
> +			of_property_read_u32(cn, "clock-frequency", &rate);
> +
> +		if (!rate) {
> +			pr_err("%s missing clocks or clock-frequency properties\n",
> +			       cn->full_name);
> +			continue;
> +		}
> +
> +		if (!rate) {
> +			pr_err("%s invalid CPU frequency", cn->full_name);
>  			continue;
>  		}
>  
> -		capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency;
> +		capacity = ((rate) >> 20) * cpu_eff->efficiency;
>  
>  		/* Save min capacity of the system */
>  		if (capacity < min_capacity)
> -- 
> 2.0.0
> 

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