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Regulators attached via RPMh on Qualcomm sdm845 apparently are write-only. Specifically you can send a request for a certain voltage but you can't read back to see what voltage you've requested. What this means is that at bootup we have absolutely no idea what voltage we could be at. As discussed in the patches to try to support the RPMh regulators [1], the fact that regulators are write-only means that its driver's get_voltage_sel() should return an error code if it's called before any calls to set_voltage_sel(). This causes problems in machine_constraints_voltage() when trying to apply the constraints. A proposed fix was to come up with an error code that could be returned by get_voltage_sel() which would cause the regulator framework to simply try setting the voltage with the current constraints. In this patch I propose the error code -ENOTRECOVERABLE. In errno.h this error is described as "State not recoverable". Though the error code was originally intended "for robust mutexes", the description of the error code seems to apply here because we can't read the state of the regulator. Also note that the only existing user of this error code in the regulator framework is tps65090-regulator.c which returns this error code from the enable() call (not get_voltage() or get_voltage_sel()), so there should be no existing regulators that might accidentally get the new behavior. (Side note is that tps65090 seems to interpret this error code to mean an error that you can't recover from rather than some data that can't be recovered). [1] https://patchwork.kernel.org/patch/10340897/ Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Mark Brown <broonie@kernel.org> |
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