linux-kernel - Re: [PATCH] usb/phy-generic: Add support for OTG VBUS supply control

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Message-ID: <20200529072036.GA32755@b29397-desktop>
Date:   Fri, 29 May 2020 07:20:14 +0000
From:   Peter Chen <peter.chen@....com>
To:     Mike Looijmans <mike.looijmans@...ic.nl>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb/phy-generic: Add support for OTG VBUS supply control

On 20-05-29 07:47:37, Mike Looijmans wrote:
> 
> Met vriendelijke groet / kind regards,
> 
> Mike Looijmans
> System Expert
> 
> 
> TOPIC Embedded Products B.V.
> Materiaalweg 4, 5681 RJ Best
> The Netherlands
> 
> T: +31 (0) 499 33 69 69
> E: mike.looijmans@...icproducts.com
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> 
> Please consider the environment before printing this e-mail
> On 28-05-2020 13:20, Peter Chen wrote:
> > On 20-05-26 16:50:51, Mike Looijmans wrote:
> > > This enables support for VBUS on boards where the power is supplied
> > > by a regulator. The regulator is enabled when the USB port enters
> > > HOST mode.
> > > 
> > Why you don't do this at your host controller driver?
> 
> That was my first thought too, but it made more sense to do it here. It's
> about how things are connected on the board, and not about the controller.
> Also makes for a consistent devicetree when using different SOCs on the same
> carrier board.

A standard interface is: port_power for hc_driver, but seems the xHCI
doesn't implement it.

> 
> I already needed this driver to properly reset the USB phy, which the
> controller driver also did not do. So it made sense to add the vbus power
> control to this driver too.
> 
> If you have a strong preference for the controller driver, I can move this
> to the DWC3 driver which happens to be the controller for the latest batch
> of SOMs.
> 

You may ask Mathias or Felipe for comments where is suitable for vbus
regulator.

> > > +
> > >   	nop->dev		= dev;
> > >   	nop->phy.dev		= nop->dev;
> > >   	nop->phy.label		= "nop-xceiv";
> > > @@ -278,6 +319,7 @@ int usb_phy_gen_create_phy(struct device *dev, struct usb_phy_generic *nop)
> > >   	nop->phy.otg->usb_phy		= &nop->phy;
> > >   	nop->phy.otg->set_host		= nop_set_host;
> > >   	nop->phy.otg->set_peripheral	= nop_set_peripheral;
> > > +	nop->phy.otg->set_vbus		= nop_set_vbus;

OTG is dead, even USB-IF has refused OTG test since 2019-09, you may
avoid to use OTG structure.

Peter


> > >   	return 0;
> > >   }
> > > diff --git a/drivers/usb/phy/phy-generic.h b/drivers/usb/phy/phy-generic.h
> > > index 7ee80211a688..a3663639ea1e 100644
> > > --- a/drivers/usb/phy/phy-generic.h
> > > +++ b/drivers/usb/phy/phy-generic.h
> > > @@ -14,7 +14,9 @@ struct usb_phy_generic {
> > >   	struct gpio_desc *gpiod_reset;
> > >   	struct gpio_desc *gpiod_vbus;
> > >   	struct regulator *vbus_draw;
> > > +	struct regulator *vbus_reg;
> > >   	bool vbus_draw_enabled;
> > > +	bool vbus_reg_enabled;
> > >   	unsigned long mA;
> > >   	unsigned int vbus;
> > >   };
> > > -- 
> > > 2.17.1
> > > 
> 
> -- 
> Mike Looijmans
> 

-- 

Thanks,
Peter Chen