From: Phil Edworthy <phil.edworthy@renesas.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
CC: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Felipe Balbi <balbi@ti.com>, Ulrich Hecht <ulrich.hecht@gmail.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        "Sergei Shtylyov" <sergei.shtylyov@cogentembedded.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-sh@vger.kernel.org" <linux-sh@vger.kernel.org>
Subject: RE: [PATCH v3] usb: renesas_usbhs: Allow an OTG PHY driver to provide
 VBUS
Thread-Topic: [PATCH v3] usb: renesas_usbhs: Allow an OTG PHY driver to
 provide VBUS
Thread-Index: AQHQt8SdC1/NhxXKPEKUq1npoPo7PZ3PttZA
Date: Tue, 7 Jul 2015 09:12:17 +0000
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 <3446210.Evs1k3c1oP@avalon>
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Hi Laurent,

On 06 July 2015 09:20, Laurent wrote:
> Hi Phil,
> 
> Thank you for the patch.
Thanks for your review!
 
> On Thursday 02 July 2015 11:26:33 Phil Edworthy wrote:
> > These changes allow a PHY driver to trigger a VBUS interrupt and
> > to provide the value of VBUS.
> >
> > Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
> >
> > ---
> > v3:
> >   - Changed how indirect vbus is plumbed in.
> >   - Removed unnecessary (void) on call to otg_set_peripheral.
> >   - Moved code that connects to bus through transceiver so it
> >     is before setting gpriv->driver.
> >
> > v2:
> >   - vbus variables changed from int to bool.
> >   - dev_info() changed to dev_err()
> > ---
> >  drivers/usb/renesas_usbhs/common.c     |  8 +++++--
> >  drivers/usb/renesas_usbhs/common.h     |  2 ++
> >  drivers/usb/renesas_usbhs/mod_gadget.c | 38
> +++++++++++++++++++++++++++++++
> >  3 files changed, 46 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/renesas_usbhs/common.c
> > b/drivers/usb/renesas_usbhs/common.c index 0f7e850..15e67d8 100644
> > --- a/drivers/usb/renesas_usbhs/common.c
> > +++ b/drivers/usb/renesas_usbhs/common.c
> > @@ -379,7 +379,10 @@ static void usbhsc_hotplug(struct usbhs_priv *priv)
> >  	/*
> >  	 * get vbus status from platform
> >  	 */
> > -	enable = usbhs_platform_call(priv, get_vbus, pdev);
> > +	if (priv->vbus_is_indirect)
> > +		enable = priv->vbus_indirect_value;
> > +	else
> > +		enable = usbhs_platform_call(priv, get_vbus, pdev);
> >
> >  	/*
> >  	 * get id from platform
> > @@ -662,7 +665,8 @@ static int usbhs_probe(struct platform_device *pdev)
> >  	pm_runtime_enable(&pdev->dev);
> >  	if (!usbhsc_flags_has(priv, USBHSF_RUNTIME_PWCTRL)) {
> >  		usbhsc_power_ctrl(priv, 1);
> > -		usbhs_mod_autonomy_mode(priv);
> > +		if (!priv->vbus_is_indirect)
> 
> Isn't this racy ? The vbus_session operation is called by transceivers from
> interrupt handlers or work queues. Do we have a guarantee that it will be
> called at least once before this code is reached ? Please see below for a
> possible way to fix this.
You are right, it is racy... :(

> > +			usbhs_mod_autonomy_mode(priv);
> >  	}
> >
> >  	/*
> > diff --git a/drivers/usb/renesas_usbhs/common.h
> > b/drivers/usb/renesas_usbhs/common.h index 8c5fc12..478700c 100644
> > --- a/drivers/usb/renesas_usbhs/common.h
> > +++ b/drivers/usb/renesas_usbhs/common.h
> > @@ -255,6 +255,8 @@ struct usbhs_priv {
> >  	struct renesas_usbhs_driver_param	dparam;
> >
> >  	struct delayed_work notify_hotplug_work;
> > +	bool vbus_is_indirect;
> > +	bool vbus_indirect_value;
> >  	struct platform_device *pdev;
> >
> >  	struct extcon_dev *edev;
> > diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c
> > b/drivers/usb/renesas_usbhs/mod_gadget.c index dc2aa32..93ad4ea 100644
> > --- a/drivers/usb/renesas_usbhs/mod_gadget.c
> > +++ b/drivers/usb/renesas_usbhs/mod_gadget.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/platform_device.h>
> >  #include <linux/usb/ch9.h>
> >  #include <linux/usb/gadget.h>
> > +#include <linux/usb/otg.h>
> >  #include "common.h"
> >
> >  /*
> > @@ -50,6 +51,7 @@ struct usbhsg_gpriv {
> >  	int			 uep_size;
> >
> >  	struct usb_gadget_driver	*driver;
> > +	struct usb_phy		*transceiver;
> >
> >  	u32	status;
> >  #define USBHSG_STATUS_STARTED		(1 << 0)
> > @@ -882,12 +884,25 @@ static int usbhsg_gadget_start(struct usb_gadget
> > *gadget, {
> >  	struct usbhsg_gpriv *gpriv = usbhsg_gadget_to_gpriv(gadget);
> >  	struct usbhs_priv *priv = usbhsg_gpriv_to_priv(gpriv);
> > +	struct device *dev = usbhs_priv_to_dev(priv);
> > +	int ret;
> >
> >  	if (!driver		||
> >  	    !driver->setup	||
> >  	    driver->max_speed < USB_SPEED_FULL)
> >  		return -EINVAL;
> >
> > +	/* connect to bus through transceiver */
> > +	if (!IS_ERR_OR_NULL(gpriv->transceiver)) {
> > +		ret = otg_set_peripheral(gpriv->transceiver->otg,
> > +					&gpriv->gadget);
> > +		if (ret) {
> > +			dev_err(dev, "%s: can't bind to transceiver\n",
> > +				gpriv->gadget.name);
> > +			return ret;
> > +		}
> > +	}
> > +
> 
> How is this change related to the topic ? I'm not too familiar with this
> driver so I might just have missed something, but then others could as well,
> and the commit message could do with a bit more information.
I'm not sure what you mean, this code is needed to tell the phy driver
if it is in host or gadget mode. I would have thought this is clear as it calls
otg_set_peripheral.

> >  	/* first hook up the driver ... */
> >  	gpriv->driver = driver;
> >
> > @@ -900,6 +915,10 @@ static int usbhsg_gadget_stop(struct usb_gadget
> > *gadget) struct usbhs_priv *priv = usbhsg_gpriv_to_priv(gpriv);
> >
> >  	usbhsg_try_stop(priv, USBHSG_STATUS_REGISTERD);
> > +
> > +	if (!IS_ERR_OR_NULL(gpriv->transceiver))
> > +		otg_set_peripheral(gpriv->transceiver->otg, NULL);
> > +
> >  	gpriv->driver = NULL;
> >
> >  	return 0;
> > @@ -947,12 +966,27 @@ static int usbhsg_set_selfpowered(struct usb_gadget
> > *gadget, int is_self) return 0;
> >  }
> >
> > +static int usbhsg_vbus_session(struct usb_gadget *gadget, int is_active)
> > +{
> > +	struct usbhsg_gpriv *gpriv = usbhsg_gadget_to_gpriv(gadget);
> > +	struct usbhs_priv *priv = usbhsg_gpriv_to_priv(gpriv);
> > +	struct platform_device *pdev = usbhs_priv_to_pdev(priv);
> > +
> > +	priv->vbus_is_indirect = 1;
> 
> vbus_is_indirect is never reset to 0. Shouldn't you set it to 1 (or rather to
> true) in usbhs_mod_gadget_probe() if an external transceiver is found ?
Yes, I see what you say.

> What would you think of implementing and wiring up the get_vbus operation in
> usbhs_mod_gadget_probe() in the same way that
> usbhs_mod_autonomy_mode() does,
> and return the value of vbus_indirect_value there ? You could then get rid of
> the vbus_is_indirect field and move the vbus_indirect_value field to struct
> usbhsg_gpriv, removing the need to modify
> drivers/usb/renesas_usbhs/common.c.
> It should also solve the race condition mentioned above.
Ok, I'll have a look at that.
 
> > +	priv->vbus_indirect_value = !!is_active;
> > +
> > +	renesas_usbhs_call_notify_hotplug(pdev);
> > +
> > +	return 0;
> > +}
> > +
> >  static const struct usb_gadget_ops usbhsg_gadget_ops = {
> >  	.get_frame		= usbhsg_get_frame,
> >  	.set_selfpowered	= usbhsg_set_selfpowered,
> >  	.udc_start		= usbhsg_gadget_start,
> >  	.udc_stop		= usbhsg_gadget_stop,
> >  	.pullup			= usbhsg_pullup,
> > +	.vbus_session		= usbhsg_vbus_session,
> >  };
> >
> >  static int usbhsg_start(struct usbhs_priv *priv)
> > @@ -994,6 +1028,10 @@ int usbhs_mod_gadget_probe(struct usbhs_priv
> *priv)
> >  		goto usbhs_mod_gadget_probe_err_gpriv;
> >  	}
> >
> > +	gpriv->transceiver = usb_get_phy(USB_PHY_TYPE_UNDEFINED);
> > +	dev_info(dev, "%s transceiver found\n",
> > +		 gpriv->transceiver ? "" : "No");
> > +
> >  	/*
> >  	 * CAUTION
> >  	 *
> 
> --
> Regards,
> 
> Laurent Pinchart

Thanks
Phil
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