Ulf, On Tue, Mar 17, 2015 at 3:23 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: >> This will get us within .3V of whatever vmmc is. If vmmc is 3.3V, it >> will allow vqmmc of 3.0V - 3.6V. >> >> This _seems_ sane to me and given any sane system design we should be >> fine here, I think. I can't see someone designing a system where >> vqmmc was not within .3V of vmmc, can you? If we think someone will >> actually build a system where vmmc is 3.3V and vqmmc can't go higher >> than 2.7V then we'll either need to increase the tolerance here or add >> a new asymmetric system call like my original patches did. > > I know about SoC that supports 3.4V vmmc and 2.9V vqmmc. > > What I think we need is the option to have a policy here. We need to > allow voltage levels stated by the spec and at the same time try chose > the one best suited. That's not being accomplished here. > > Moreover, I wonder whether it's okay (from spec perspective) to have > vqmmc at a higher voltage level than vmmc. I don't think that's > allowed, but I might be wrong. OK, so sounds like I need to add a regulator_set_voltage_tol2() function that takes in an upper tolerance and a lower. We can use the same rough implementation in the core we have today (if Mark is OK with that) with regulator_set_voltage_tol() but just allow it to be asymmetric. >From what I see in the spec for 3.3V cards are supposed to react to a high signal that is .625 * VDD - VDD + .3 I might not be able to get to this till next week, though... -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
