On Mon, Jun 17, 2019 at 1:24 PM Mark Brown <broonie@xxxxxxxxxx> wrote: > > On Mon, Jun 17, 2019 at 01:06:42PM -0600, Jeffrey Hugo wrote: > > On Mon, Jun 17, 2019 at 12:37 PM Mark Brown <broonie@xxxxxxxxxx> wrote: > > > > Something really weird is going on with the word wrapping in your mail, > > > it looks like you're writing lines longer than 80 characters (120?) and > > > they're getting a newline added in the middle of the line to wrap them > > > without reflowing the paragraph. > > > Doh. Hopefully this one is better. > > Yes, thanks! Though now it's off-list :/ Doh. Added everyone back. > > > > Well, it doesn't *have* to be the raw register value, more accurately > > > it's some token which is useful for passing to and from the hardware; > > > The documentation such as it > > > is is in the documentation of the list_voltage() operation (which is > > > what defines the selector values for a given driver). > > > Ok, so this one bit - > > Selectors range from zero to one less than regulator_desc.n_voltages. > > Voltages may be reported in any order. > > Yes. > > > So, I understand that. Its an indexing of the supported voltages. > > From my perspective, that has nothing to do with hardware. Its just a > > remapping of the values to a different set. Voltages X, Y, and Z map > > to 0, 1, and 2. Its a token so that the driver and the framework can > > use a common value. > > > I really think we are on the same page here, its just I was getting > > confused by how you were describing it in your replies. > > Yes, I was just coming from the perspective that for almost all hardware > the selectors are chosen to be the values that are in the bitfield that > the hardware uses to specify the voltage since that's the most common > thing and tends to make things simpler for people, it's also the primary > place where the concept came from. > > > > Your idea of very basic implementations is how the overwhelming majority > > > of hardware is implemented. Regulators with register maps will tend to > > > just have a bitfield where you set the voltage with each valid value in > > > that bitfield mapped to a single voltage, the exceptions tend to use > > > direct voltage values instead (and not support enumeration at all). > > > > Looking at the driver I think it's got what the helpers are terming > > > pickable linear ranges (naming is hard) and could use those helpers. > > > I'm pretty sure Stephen Boyd and Bjorn just investigated that a few > > weeks ago, and came to the conclusion that it can't because of things > > like the hardware really wants to stay in the same range if at all > > possible, which is not behavior the pickable linear ranges seems to > > support. > > Sounds like it just needs a custom map_voltage() function? Though > thinking about it it's possibly worth just making the standard map try > to keep things in the same range as that will if nothing else reduce the > number of I/O operations. Probably also reduce glitches if there's > overlapping ranges. I didn't think so when I was paying attention to their discussion. However maybe I missed something. I think I'll take another look. Might make for a nice cleanup, but if its just in the driver, or if it involves updating the framework, it seems to be outside scope for this series of changes.
