On 04/29/2016 06:44 PM, Mark Brown wrote: > On Fri, Apr 29, 2016 at 01:55:14PM +0200, Krzysztof Kozlowski wrote: >> On 04/29/2016 01:30 PM, Mark Brown wrote: > >>> Supplies are only optional if they may be physically absent. In this >>> case it's possible that on device regulators may be used instead, a >>> pattern more like that used for arizona-ldo1 where we represent those >>> regulators might be better as it's more clearly describing the >>> situation. I'm just wondering if the supply lookup stuff there should >>> be factored out as this is not an uncommon pattern.. > >>> It should at least be clearly stated what's going on, ignoring failure >>> to get supplies is generally a bug and people will tend to blindly cut >>> and paste things (witness all the breakage in graphics drivers with >>> this). > >> The VDD33 is really optional. The device can work in different >> configuration, e.g. only on VBAT. How the reset logic would work then? I >> don't know... I would suspect that it could be exactly the same (just >> replace VDD33 with VBAT) but I am not sure. > > What the Arizona example I mentioned does is look for the property > specifying an external supply in DT and if there isn't one assumes that > it must be using the internal regulator. That's a bit icky but it does > the right thing and is much simpler from a user point of view. Okay, that indeed looks similar... in case of lack of external supplies the usb3503 pins should be tied to the internal regulators. However it seems I was wrong at the beginning. We've been looking here at the schematics and the datasheet. The design is unfortunately a little bit confusing but finally I think we got the impression how does it work. This VDD regulator supply actually is not a usb3503 USB HUB regulator supply... but a supply to the LAN attached to this HUB. Regulator off/on is needed for LAN to show up. The hub will show up with typical reset (which is also missing before my patchset btw). The LAN, as a USB device, is auto-probed so it cannot take the regulator and play with it. The simplest idea I have is to add it as "external supply" to the parent: usb3503. Best regards, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
