On Thu, Sep 22, 2016 at 11:51:02AM -0700, Stephen Boyd wrote: > Quoting Peter Chen (2016-09-16 18:16:05) > > On Wed, Sep 14, 2016 at 01:55:02AM -0700, Stephen Boyd wrote: > > > Quoting Stephen Boyd (2016-09-13 18:42:46) > > > > On the db410c 96boards platform we have a TC7USB40MU[1] on the > > > > board to mux the D+/D- lines from the SoC between a micro usb > > > > "device" port and a USB hub for "host" roles. Upon a role switch, > > > > we need to change this mux to forward the D+/D- lines to either > > > > the port or the hub. Therefore, introduce a driver for this > > > > device that intercepts extcon USB_HOST events and logically > > > > asserts a gpio to mux the "host" D+/D- lines when a host cable is > > > > attached. When the cable goes away, it will logically deassert > > > > the gpio and mux the "device" lines. > > > > > > > > [1] https://toshiba.semicon-storage.com/ap-en/product/logic/bus-switch/detail.TC7USB40MU.html > > > > > > > > Cc: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx> > > > > Cc: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> > > > > Cc: <devicetree@xxxxxxxxxxxxxxx> > > > > Signed-off-by: Stephen Boyd <stephen.boyd@xxxxxxxxxx> > > > > --- > > > > > > > > Should I make the extcon part optional? I could see a case where there are two > > > > "OTG" ports connected to the mux (or two hubs), and for some reason the > > > > software may want to mux between them at runtime. If we mandate an extcon, > > > > that won't be possible to support. Perhaps it would be better to have > > > > the node, but connect it to the usb controller with a phandle (maybe of_graph > > > > endpoints would be useful too) so that when the controller wants to mux over > > > > a port it can do so. > > > > > > Here's some dts mock-up on top of the db410c for the of_graph stuff. I > > > haven't written any code around it, but the idea is to allow the binding > > > to specify how the mux is connected to upstream and downstream D+/D- > > > lines. This way, we can do some dt parsing of the endpoints and their > > > parent nodes to figure out if the mux needs to be set high or low to use > > > a device connector or a usb hub based on if the id cable is present. > > > Maybe I'm over thinking things though and we could just have a DT > > > property for that. > > > > > > soc { > > > usb@78d9000 { > > > extcon = <&usb_id>, <&usb_id>; > > > > Why you have two same extcon phandler? From my mind, one should id, > > another should is vbus. Besides, I find extcon-usb-gpio.c is lack of > > vbus support, how you support vbus detection for > > connection/disconnection with PC for your chipidea msm patch set? > > This was already in the dts files for db410c. In the chipidea binding > one is for EXTCON_USB (vbus) and one is for EXTCON_USB_HOST (id). My > understanding is that extcon-usb-gpio.c sends events for both EXTCON_USB > and EXTCON_USB_HOST when the gpio changes state. vbus detection is not > that great on this board because we only have on gpio for this. I think extcon-usb-gpio.c needs to extend for supporting vbus event, otherwise, the micro-b cable's connect/disconnect will introduce EXTCON_USB_HOST event, if you use two <&usb_idx> for both id and vbus event. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
