Re: Plain DFS (no voltage scaling)

[Mason <slash.tmp@free.fr>]

On 03/02/2016 17:14, Viresh Kumar wrote:
> On 03-02-16, 16:35, Mason wrote:
>> On 03/02/2016 03:10, Viresh Kumar wrote:
>>> On 02-02-16, 22:11, Mason wrote:
>>>> Hello,
>>>>
>>>> I plan to enable the on-demand governor on the tango platform:
>>>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/tango4-smp8758.dtsi
>>>>
>>>> I found the cpufreq-dt binding doc:
>>>>
>>>> https://www.kernel.org/doc/Documentation/devicetree/bindings/cpufreq/cpufreq-dt.txt
>>>> https://www.kernel.org/doc/Documentation/devicetree/bindings/opp/opp.txt
>>>>
>>>> Something is not clear to me:
>>>>
>>>> If my platform cannot scale the voltage, what information
>>>> should I put in the voltage part of the DT?
>>>
>>> Wouldn't matter if there is no regulator. i.e. you should keep 0, but
>>> even if they have something non-zero, core code will ignore it. But
>>> yeah, it makes sense to keep it zero.
>>
>> Hmmm, I am missing something obvious.
>>
>> My config contains:
>>
>> CONFIG_CPU_FREQ=y
>> CONFIG_CPU_FREQ_GOV_COMMON=y
>> CONFIG_CPU_FREQ_STAT=y
>> CONFIG_CPU_FREQ_STAT_DETAILS=y
>> CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y
>> CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
>> CONFIG_CPU_FREQ_GOV_ONDEMAND=y
>> CONFIG_CPUFREQ_DT=y
>>
>> Yet, neither dt_cpufreq_probe() nor cpufreq_init() are being called.
>>
>> Could someone please point to my mistake?
> 
> You need to create a platform device to get cpufreq-dt driver probed.
> Check other users..

The sunxi guys pointed me in the right direction.

http://lxr.free-electrons.com/source/arch/arm/mach-sunxi/sunxi.c#L20

Why isn't there a compatible string like other drivers?

Such as
  compatible = "cpufreq-dt"
which would enable cpufreq on the platform?

Regards.