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 RK808_BUCK1_ON_VSEL_REG, and when we pull up DVSn pin, the voltage value if from RK808_BUCK1_ON_VSEL_REG+2. 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 load. 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.
