Hi, On Mon, Aug 15, 2016 at 09:21:25PM +0200, Hans de Goede wrote: > Hi All, > > Here is a patch series which implements run-time changing the dr-mode > of sunxi musb controllers through the (already existing) musb "mode" > sysfs attribute. > > This is useful on boards where there is no id pin, e.g. some tv-boxes > use the musb controller to get an extra usb A port without needing > a hub chip. Except for the missing id pin when using a usb A<->A cable > these ports can do peripheral mode just fine. This series makes it > possible to do e.g. this by doing echo "peripheral" > mode before > plugging in the usb A<->A cable. Well, this is an illegal usecase. A-A cable is invalid by USB Spec. With type-A receptacle the controller should be in host-only mode, switching to peripheral mode should not be allowed. > > This series has both sun4i-usb-phy driver and sunxi-musb-glue changes, > both are necessary for the run-time changing to work, but they can be > merged independently without breaking anything. > > Changed in v2: > > After sleeping on it a night I realized that always passing port_mode = > DUAL_ROLE to the musb-core was wrong. There is a distintion between > the id-pin not working properly which we can work around with software > mode switching (and we want to register both the host and udc driver > in this case) vs cases where we really only want to register a host > (wifi module connected to musb soldered onto the PCB). > > So v2 of this series drops the > "musb: sunxi: Always register both host and udc when build with dual-role support" > patch. > > Instead systems which are dual-role capable, but lack an id-pin should use > dr_mode = "otg" in the dts file. There is one problem with this, some > systems are dual-role capable but use a female USB-A connector connected > to the musb controller. These should come up in host mode by default, This is not a problem. With a type-A connector, the dual-role controller should work in host-only mode. Role switching should only be allowed if an AB connector is used. Using the sysfs entry to switch roles for generic purpose is really a bad idea, it opens up ton of problems. For systems which lack of id-pin should use a discrete circuit (for example GPIO) to detect the id pin in the AB receptacle, then the USB driver will handle the role switching transparently. > rather then peripheral mode which is the default for systems which lack an > id-pin. This patch set introduces: > > "phy-sun4i-usb: Add "allwinner,usb0-usb-a-connector" dt property" > > Which allows specifying the use of a female USB-A connector for the > musb controller in the phy dt node, the presence of this dt property > changes the default to host mode. This is unnecessary, if using a type-A connector, dr_mode should be "host" in DT. > > Please review (and if no issues are found merge). > > Thanks & Regards, > > Hans Regards, -Bin. -- 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
