On Wed, Feb 03, 2016 at 01:39:02PM +0800, menghui lin wrote: > On Tue, 2016-02-02 at 19:38 +0000, Mark Brown wrote:
> > How does the driver know if it needs to change the mode (ie, how can it > > tell if the current mode is inadequate) and surely if we can only change > > in one direction this isn't terribly useful? > I think the datasheet of buck/ldo could provide information about power > capability of each mode. The driver should adjust regulator mode per its > device's power requirement. That's of no help for a consumer driver which doesn't know what regulator is supplying it. > case 1: > We have a USB typeC micro-controller, which has two modes - standby and > normal. It requires 1.8V and 3.3V to operate (both powers are always > on). The device stays in standby mode when there is no cable in. When > cable in, we got an interrupt and change device into normal mode. > The standby mode power consumption is quite small, so we would like the > change mode of regulator into STANDBY to save more power. And we change > into NORMAL when we receive cable-in interrupt. This seems like something that we ought to be doing via runtime PM anyway which should be going through the suspend mode bindings, though that would need some plumbing in. > case 2: > About buck regulator for CPU, it usually provides PWM mode, PWM/PFM Auto > mode, PFM mode. I think it could map to FAST, NORMAL, IDLE mode > respectively. Most of time we would use just normal mode. However, we > would change regulator into PWM mode time to time to test buck output > performance on the tested board. That's a test use that doesn't seem a good fit for upstream at all.
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