[PATCH v3 2/2] regulator: rk808: add dvs support

Chris Zhong zyw at rock-chips.com
Tue Dec 30 18:21:42 PST 2014

On 12/31/2014 01:04 AM, Mark Brown wrote:
> On Tue, Dec 30, 2014 at 11:07:14AM +0800, Chris Zhong wrote:
>> On 12/30/2014 01:25 AM, Mark Brown wrote:
>>> So, this seems a bit odd.  What we appear to be doing here is
>>> alternating between the two different voltage setting registers which is
>>> all well and good but makes me wonder why we're bothering - it's a bit
>>> more work than just sticking with one.  We do get...
>> you mean check the old_selector and selector? I think
>> _regulator_do_set_voltage have done it.
> No, I mean that we may as well just always write to the same register
> and save a bunch of code.
No, when we pull down DVSn pin, the voltage value is from 
and when we pull up DVSn pin, the voltage value if from 
We want to this dvs function for a better voltage wave, avoid overshoot, 
if someone do not
need this function, they could remove the setting of DVSn pin in dts 
file, and at that time,
rk808_regulator will use a same register for setting voltage.

>>> ...this but unless the voltage typically ramps much faster than spec
>>> it's never clear to me that we're actually winning by polling the pin
>>> instead of just dead reckoning the time, it's more work for the CPU to
>>> poll the GPIO than to sleep after all.
>> Actually, it's slower than spec, so I think getting this dvsok pin state
>> is safer than delay.
> Well, that suggests that the spec is wrong which ought to be fixed
> anyway oughtn't it?  Or are you saying that the delay is inconsistent as
> well as slower than advertised?
the spec said 2/4/6/10 mv/us, but the ramp will change depending on the 
So I think the dvsok pin is more accurate, since it It will soon change, 
once the
regulator is completed. the delay is a fixed time. it is faster than 
dvsok pin.

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