i'm still working on regulator support for Linux Mainline and have some questions about the LINREGs and DC-DC on the i.MX28 PMU.
1. Which of the Linux modes (see below) could be mapped for LINREGs and DC-DC?
2. Looking at the FSL BSP (2.6.35) shows that FAST mode for LINREGs is implemented as DISABLE_STEPPING=1. Is the implementation correct?
3. Are there any useful LINREG settings for idle state?
4. What are the relevant DC-DC settings for the Linux regulator modes?
Here is a quote of the possible operating modes of a regulator (this includes also the DC-DC):
* Regulator operating modes.
* Regulators can run in a variety of different operating modes depending on
* output load. This allows further system power savings by selecting the
* best (and most efficient) regulator mode for a desired load.
* Most drivers will only care about NORMAL. The modes below are generic and
* will probably not match the naming convention of your regulator data sheet
* but should match the use cases in the datasheet.
* In order of power efficiency (least efficient at top).
* Mode Description
* FAST Regulator can handle fast changes in it's load.
* e.g. useful in CPU voltage & frequency scaling where
* load can quickly increase with CPU frequency increases.
* NORMAL Normal regulator power supply mode. Most drivers will
* use this mode.
* IDLE Regulator runs in a more efficient mode for light
* loads. Can be used for devices that have a low power
* requirement during periods of inactivity. This mode
* may be more noisy than NORMAL and may not be able
* to handle fast load switching.
* STANDBY Regulator runs in the most efficient mode for very
* light loads. Can be used by devices when they are
* in a sleep/standby state. This mode is likely to be
* the most noisy and may not be able to handle fast load
Thanks in advance