linux-kernel - Re: [PATCH v4 3/4] dt-bindings: Add Qualcomm USB SuperSpeed PHY bindings

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Message-ID: <5d71edf5.1c69fb81.1f307.fdd6@mx.google.com>
Date:   Thu, 05 Sep 2019 22:26:12 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Jack Pham <jackp@...eaurora.org>,
        Jorge Ramirez <jorge.ramirez-ortiz@...aro.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>, robh@...nel.org,
        andy.gross@...aro.org, shawn.guo@...aro.org,
        gregkh@...uxfoundation.org, mark.rutland@....com, kishon@...com,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, khasim.mohammed@...aro.org
Subject: Re: [PATCH v4 3/4] dt-bindings: Add Qualcomm USB SuperSpeed PHY bindings

Quoting Jack Pham (2019-09-05 10:58:02)
> Hi Jorge, Bjorn,
> 
> On Thu, Sep 05, 2019 at 09:18:57AM +0200, Jorge Ramirez wrote:
> > On 9/4/19 01:34, Bjorn Andersson wrote:
> > > On Tue 03 Sep 14:45 PDT 2019, Stephen Boyd wrote:
> > >> that would need an of_regulator_get() sort of API that can get the
> > >> regulator out of there? Or to make the connector into a struct device
> > >> that can get the regulator out per some generic connector driver and
> > >> then pass it through to the USB controller when it asks for it. Maybe
> > >> try to prototype that out?
> > >>
> > > 
> > > The examples given in the DT bindings describes the connector as a child
> > > of a PMIC, with of_graph somehow tying it to the various inputs. But in
> > > these examples vbus is handled by implicitly inside the MFD, where
> > > extcon is informed about the plug event they toggle vbus as well.
> > > 
> > > In our case we have a extcon-usb-gpio to detect mode, which per Jorge's
> > > proposal will trickle down to the PHY and become a regulator calls on
> > > either some external regulator or more typically one of the chargers in
> > > the system.
> 
> Interesting you mention extcon-usb-gpio. I thought extcon at least from
> bindings perspective is passÃ© now. Maybe this is what you need (just
> landed in usb-next):
> 
> usb: common: add USB GPIO based connection detection driver
> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/commit/?h=usb-next&id=4602f3bff2669012c1147eecfe74c121765f5c56
> 
> dt-bindings: usb: add binding for USB GPIO based connection detection driver
> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/commit/?h=usb-next&id=f651c73e71f53f65e9846677d79d8e120452b59f
> 
> Fortunately this new driver might check the right boxes for you:
> - usb connector binding
> - ID detect GPIO
> - vbus-supply regulator
> 
> With that, I think you can also keep the connector subnode out of the
> SSPHY node well, and similarly get rid of the vbus toggle handling from
> the PHY driver.
> 
> The big thing missing now is that this driver replaces extcon
> completely, so we'll need handling in dwc3/dwc3-qcom to retrieve the
> role switch state to know when host mode is entered. I saw this a while
> back but don't think it got picked up:
> 
> https://patchwork.kernel.org/patch/10909981/
> 

Yes this looks like the approach that should be taken. One question
though, is this a micro-b connector or a type-c connector on the board?
I thought it was a type-c, so then this USB gpio based connection driver
isn't an exact fit?