13.11.2020 19:15, Mark Brown пишет: > On Fri, Nov 13, 2020 at 06:55:27PM +0300, Dmitry Osipenko wrote: >> 13.11.2020 17:29, Mark Brown пишет: > >>> It's not clear if it matters - it's more a policy decision on the part >>> of the driver about what it thinks safe error handling is. If it's not > >> If regulator_get() returns a dummy regulator, then this means that >> regulator isn't specified in a device-tree. But then the only way for a >> consumer driver to check whether regulator is dummy, is to check >> presence of the supply property in a device-tree. > > My point here is that the driver shouldn't be checking for a dummy > regulator, the driver should be checking the features that are provided > to it by the regulator and handling those. I understand yours point, but then we need dummy regulator to provide all the features, and currently it does the opposite. > It doesn't matter if this is > a dummy regulator or an actual regulator with limited features, the > effect is the same and the handling should be the same. If the driver > is doing anything to handle dummy regulators explicitly as dummy > regulators it is doing it wrong. It matters because dummy regulator errors out all checks and changes other than enable/disable, instead of accepting them. If we could add an option for dummy regulator to succeed all the checks and accept all the values, then it could become more usable. >> We want to emit error messages when something goes wrong, for example >> when regulator voltage fails to change. It's fine that voltage changes >> are failing for a dummy regulator, but then consumer driver shouldn't >> recognize it as a error condition. > > If you're fine with that you should also be fine with any other > regulator for which you failed to enumerate any voltages which you can > set. It's not fine. In the case of this driver the dummy regulator should succeed instead of failing. >> The regulator_get_optional() provides a more consistent and >> straightforward way for consumer drivers to check presence of a physical >> voltage regulator in comparison to dealing with a regulator_get(). The >> dummy regulator is nice to use when there is no need to change >> regulator's voltage, which doesn't work for a dummy regulator. > > To repeat you should *only* be using regulator_get_optional() in the > case where the supply may be physically absent which is not the case > here. > Alright, but then we either need to improve regulator core to make dummy regulator a bit more usable, or continue to work around it in drivers. What should we do?
