From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Boyd Subject: Re: [RFC/PATCH] usb: misc: Add a driver for TC7USB40MU Date: Thu, 22 Sep 2016 11:51:02 -0700 Message-ID: <147457026249.9057.8712383708019243942@sboyd-linaro> References: <20160914014246.31847-1-stephen.boyd@linaro.org> <147384330268.13546.17843140335600627152@sboyd-linaro> <20160917011605.GB10392@b29397-desktop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160917011605.GB10392@b29397-desktop> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Peter Chen Cc: devicetree@vger.kernel.org, Peter Chen , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Chanwoo Choi , robh+dt@kernel.org, MyungJoo Ham , linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-arm-msm@vger.kernel.org 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 > > > Cc: Chanwoo Choi > > > Cc: > > > Signed-off-by: Stephen Boyd > > > --- > > > > > > 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. From mboxrd@z Thu Jan 1 00:00:00 1970 From: stephen.boyd@linaro.org (Stephen Boyd) Date: Thu, 22 Sep 2016 11:51:02 -0700 Subject: [RFC/PATCH] usb: misc: Add a driver for TC7USB40MU In-Reply-To: <20160917011605.GB10392@b29397-desktop> References: <20160914014246.31847-1-stephen.boyd@linaro.org> <147384330268.13546.17843140335600627152@sboyd-linaro> <20160917011605.GB10392@b29397-desktop> Message-ID: <147457026249.9057.8712383708019243942@sboyd-linaro> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 > > > Cc: Chanwoo Choi > > > Cc: > > > Signed-off-by: Stephen Boyd > > > --- > > > > > > 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 at 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.