On Thu, Jul 05, 2012 at 04:43:27PM +0900, Alex Courbot wrote: > On 07/05/2012 03:47 PM, Sascha Hauer wrote: > >>I thought about just checking if devm_get_regulator returned -ENODEV > >>and happily continue if that was the case, assuming no regulator was > >>declared. > > > >And that's the problem. The get_regulator won't return -ENODEV. It will > >return -EPROBE_DEFER which tells you nothing about whether a regulator > >will ever be available or not. > > > >Having a flag in platform data would be fine with me, but I know other > >people think differently. > > > >BTW in devicetree this flag implicitely exists with the power-supply > >property. > > One could actually question whether the whole regulator/gpio thing > should be supported at all with platform data. The platform > interface can use the function hooks in order to implement whatever > behavior it wants when the light needs to be powered on and off. The > reason for introducing optional regulator/gpio parameters is because > the DT cannot use these. Since I have no plan to remove these > function hooks, making the regulator/gpio option available in > platform data might be redundant. Any thought about this? I agree. Non-DT platforms have always used the callbacks to execute this kind of code. As you've said before there are situations where it isn't just about setting a GPIO or enabling a regulator but it also requires a specific timing. Representing this in the platform data would become tedious. So I think for the DT case you can parse the power-on and power-off sequences directly and execute code based on it, while in non-DT cases the init and exit callbacks should be used instead. I think it even makes sense to reuse the platform data's init and exit functions in the DT case and implement the parser/interpreter within those. > >Right now the regulator core will just return -EPROBE_DEFER in both > >cases. This could easily be changed in the regulator core. > > Could this be because the regulator core cannot make the difference > between a not-yet-available regulator and a missing one? I case where the regulator comes from a DT it should assume that it will become available at some point, so -EPROBE_DEFER is correct. However if the DT doesn't even contain the power-supply property, then EPROBE_DEFER will never work because there's no regulator to become available. Thierry
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