10.11.2020 23:32, Mark Brown пишет:

On Tue, Nov 10, 2020 at 09:29:45PM +0100, Thierry Reding wrote:

quoted

On Thu, Nov 05, 2020 at 02:44:08AM +0300, Dmitry Osipenko wrote:

quoted

quoted

+	/*
+	 * 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;

quoted

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.