10.11.2020 23:32, Mark Brown пишет:
On Tue, Nov 10, 2020 at 09:29:45PM +0100, Thierry Reding wrote:
On Thu, Nov 05, 2020 at 02:44:08AM +0300, Dmitry Osipenko wrote:
- /*
* Voltage scaling is optional and trying to set voltage for a dummy* regulator will error out.*/- if (!device_property_present(dc->dev, "core-supply"))
return;This is a potentially heavy operation, so I think we should avoid that here. How about you use devm_regulator_get_optional() in ->probe()? That returns -ENODEV if no regulator was specified, in which case you can set dc->core_reg = NULL and use that as the condition here.
Or enumerate the configurable voltages after getting the regulator and handle that appropriately which would be more robust in case there's missing or unusual constraints.
I already changed that code to use regulator_get_optional() for v2.
Regarding the enumerating supported voltage.. I think this should be done by the OPP core, but regulator core doesn't work well if regulator_get() is invoked more than one time for the same device, at least there is a loud debugfs warning about an already existing directory for a regulator. It's easy to check whether the debug directory exists before creating it, like thermal framework does it for example, but then there were some other more difficult issues.. I don't recall what they were right now. Perhaps will be easier to simply get a error from regulator_set_voltage() for now because it shouldn't ever happen in practice, unless device-tree has wrong constraints.