OPP: how to get the all frequency list?

OPP: how to get the all frequency list?

[Chanwoo Choi]

Dear all,

I have a question that how to get the all frequency list
by using the OPP interface. (It doesn't matter whether frequency is available or not.)

OPP has following three functions in order to find the proper frequency.
- dev_pm_opp_find_freq_exact(struct device *dev, unsigned long freq, bool available);
- dev_pm_opp_find_freq_floor(struct device *dev, unsigned long freq);
	: Search for a rounded floor freq (if opp->available is true)
- dev_pm_opp_find_freq_ceil(struct device *dev, unsigned long freq);
	: Search for a rounded ceil freq if (opp->available is true)

In this case,
when the device using OPP tries to find the all frequencies,
the device can't find them. The device can just find the available frequencies.

If the some frequency of the device might be disabled by dev_pm_opp_disable()
and also the device doesn't know the correct frequency value,
the device cannot find the all frequencies by using the dev_pm_opp_find_freq_floor/ceil()

It is just able to find the available frequencies if opp->available is true.

Or
When proving the device driver and then before disabling the OPP by dev_pm_opp_disable(),
each device driver have to store the frequency lists on the private data structure.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

Re: OPP: how to get the all frequency list?

[Viresh Kumar]

On 21-08-17, 17:53, Chanwoo Choi wrote:
> Dear all,
> 
> I have a question that how to get the all frequency list
> by using the OPP interface. (It doesn't matter whether frequency is available or not.)
> 
> OPP has following three functions in order to find the proper frequency.
> - dev_pm_opp_find_freq_exact(struct device *dev, unsigned long freq, bool available);
> - dev_pm_opp_find_freq_floor(struct device *dev, unsigned long freq);
> 	: Search for a rounded floor freq (if opp->available is true)
> - dev_pm_opp_find_freq_ceil(struct device *dev, unsigned long freq);
> 	: Search for a rounded ceil freq if (opp->available is true)
> 
> In this case,
> when the device using OPP tries to find the all frequencies,
> the device can't find them. The device can just find the available frequencies.
> 
> If the some frequency of the device might be disabled by dev_pm_opp_disable()
> and also the device doesn't know the correct frequency value,
> the device cannot find the all frequencies by using the dev_pm_opp_find_freq_floor/ceil()
> 
> It is just able to find the available frequencies if opp->available is true.

You can add the 'available' argument to the other APIs as well, just that you
need to justify them with proper examples.

-- 
viresh