On 12/09/2015 06:36 AM, Rob Herring wrote: > On Wed, Dec 9, 2015 at 6:55 AM, Tim Bird <tim.bird@xxxxxxxxxxxxxx> wrote: >> On 12/08/2015 08:11 PM, Rob Herring wrote: >>> On Tue, Dec 08, 2015 at 04:40:16PM -0800, Tim Bird wrote: >>>> Add a binding for the regulator which controls the OTG chargepath switch. >>>> The OTG switch gets its power from pm8941_5vs1, and that should be >>>> expressed as a usb-otg-in-supply property in the DT node for the >>>> charger driver. The regulator name is "otg". > > [...] > >>>> +child nodes: >>>> +- otg: >>>> + Usage: optional >>>> + Description: This node defines a regulator used to control the direction >>>> + of VBUS voltage - specifically: whether to supply voltage >>>> + to VBUS for host mode operation of the OTG port, or allow >>>> + input voltage from external VBUS for charging. In the >>>> + hardware, the supply for this regulator comes from >>>> + usb-otg-in-supply. >>> >>> Doesn't this regulator need to have a name defined? >> >> I'm not sure what you mean. The regulator name is "otg", defined by the DT node >> name. The code requires that the DT node name be "otg", and defines a regulator >> with the same name. >> >> As far as I know, you have to define a DT label for the node, in order >> to reference this regulator with a phandle. Is that what you are referring to? >> I usually use "chg_otg" as the label. Are you asking that this be reflected >> in the example? > > You need a regulator-name property. Also, should should define valid > values for regulator-min-microvolt and regulator-max-microvolt. All of those are listed as optional properties in Documentation/devicetree/bindings/regulator/regulator.txt. The regulator-name seems redundant, since the name of the DT node becomes the regulator name in the Linux system. This is not currently used anywhere, as the node is "connected up" via phandle, which uses the label. That is, there's no code in the kernel that looks up this regulator by name, although it does get a name. As for the microvolt references, I'm a little stumped what to do with those. I could use regulator-min-microvolt of 0 and a regulator-max-microvolt of 500000, but that's not exactly right. This is actually representing a voltage switch, which is being represented in the regulator framework in Linux, because it seems to fit there best. It has regulators it's related to, which should be adjusted when this one is. However, it intrinsically does not have a voltage of it's own, so it's a bit of a weird case. And the voltage can either be going "out" or "in". I'm CC-ing Mark Brown, who may know how these types of things are supposed to be expressed. I believe he saw an earlier version of this patch last year. Or maybe our power maintainers will chime in with some wisdom. I can't be the first person to be adding a charge pathway switch to mainline, so I'm open to doing it the "right way". :-) > Thinking about this some more, the node name should be generic, so > just "regulator". The label does not need to be generic. There are other switches in the charger block that are not exposed yet. This one handles the the OTG (vbus) charge pathway. Others handle other charge pathways (some of which are used on phones and some are not - they're used, e.g., on the dragonboard). I'd rather not give it a generic name, because eventually the driver should expose those other switches as something as well. -- Tim -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
