On Mon, Feb 04, 2019 at 11:25:10AM -0800, Bjorn Andersson wrote: > On Mon 04 Feb 10:23 PST 2019, Mark Brown wrote: > > On Mon, Feb 04, 2019 at 08:03:37AM -0800, Bjorn Andersson wrote: > Okay, I don't see a big problem with expecting the DT to only contain > values that the hardware can actually do. I do however see that > machine_constraints_voltage() has been changes to expect the driver to > return -ENOTRECOVERABLE when we don't have a way to query the voltage > during probe. > So there's a risk of this breaking compatibility with older dtb files on > other boards. We will have to do some more verification on this. That's basically only going to affect Qualcomm hardware FWIW, I had thought that such devices didn't manage to probe with upstream before that change either but I could be misremembering. > > > regulator framework be made to round down to the previous valid step > > > instead of up? > > We definitely don't want to round voltages down, it is vastly more > > common for devices to experience problems like brownouts if they go > > under voltage so it'd be more likely to cause harm than good. > We're 2mV off in this case, but it could have been way off. So I'm good > with this position. Never mind that that's 2mV assuming the regulator has perfect accuracy and there's headroom. For something like this it's likely not a problem but some high current things (especially CPUs or anything like that) are operating on thin margins.
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