Hi Thomas,

On Thu, Jan 09, 2014 at 09:29:20PM +0530, Thomas Abraham wrote:
> @@ -19,6 +19,10 @@ Optional properties:
>  - cooling-min-level:
>  - cooling-max-level:
>       Please refer to Documentation/devicetree/bindings/thermal/thermal.txt.
> +- safe-opp-index: Certain platforms require that during a opp transition,
> +  a system should not go below a particular opp level. For such systems,
> +  this property specifies the minimum opp to be maintained during the
> +  opp transitions.

<snip>

> @@ -165,13 +196,27 @@ static int cpu0_cpufreq_probe(struct platform_device 
> *pdev)
>               goto out_put_node;
>       }
>  
> +     if (!of_property_read_u32(np, "safe-opp-index", &safe_opp_index)) {
> +             rcu_read_lock();
> +             opp = dev_pm_opp_find_freq_exact(cpu_dev,
> +                     freq_table[safe_opp_index].frequency * 1000, true);

The property safe_opp_index is directly used to index freq_table here.
It only works when the opp table in device tree is defined in increasing
order.  But we have nothing in opp binding bindings/power/opp.txt to
enforce it.  That said, opp table in device tree could be in arbitrary
order, and thus safe_opp_index gives you nothing reliable.

Shawn

> +             if (IS_ERR(opp)) {
> +                     rcu_read_unlock();
> +                     pr_err("safe opp index %d is invalid\n",
> +                                                     safe_opp_index);
> +                     goto out_free_table;
> +             }
> +             safe_voltage = dev_pm_opp_get_voltage(opp);
> +             safe_frequency = freq_table[safe_opp_index].frequency;
> +             rcu_read_unlock();
> +     }
> +
>       of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
>  
>       if (of_property_read_u32(np, "clock-latency", &transition_latency))
>               transition_latency = CPUFREQ_ETERNAL;
>  
>       if (!IS_ERR(cpu_reg)) {
> -             struct dev_pm_opp *opp;
>               unsigned long min_uV, max_uV;
>               int i;
>  
> -- 
> 1.6.6.rc2
> 

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