linux-kernel - RE: [PATCH v6 07/12] usb: otg: add OTG/dual-role core

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Date:	Thu, 14 Apr 2016 11:15:16 +0000
From:	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:	Roger Quadros <rogerq@...com>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"balbi@...nel.org" <balbi@...nel.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"peter.chen@...escale.com" <peter.chen@...escale.com>
CC:	"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
	"jun.li@...escale.com" <jun.li@...escale.com>,
	"mathias.nyman@...ux.intel.com" <mathias.nyman@...ux.intel.com>,
	"tony@...mide.com" <tony@...mide.com>,
	"Joao.Pinto@...opsys.com" <Joao.Pinto@...opsys.com>,
	"abrestic@...omium.org" <abrestic@...omium.org>,
	"r.baldyga@...sung.com" <r.baldyga@...sung.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
Subject: RE: [PATCH v6 07/12] usb: otg: add OTG/dual-role core

Hi,

> From: Roger Quadros
> Sent: Thursday, April 14, 2016 8:00 PM
> 
> On 14/04/16 11:36, Yoshihiro Shimoda wrote:
> > Hi,
> >
< snip >
> > diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c
> > index e3d0161..8b74715 100644
> > --- a/drivers/usb/common/common.c
> > +++ b/drivers/usb/common/common.c
> > @@ -233,6 +233,8 @@ int of_usb_update_otg_caps(struct device_node *np,
> >  	if (of_find_property(np, "adp-disable", NULL) ||
> >  				(otg_caps->otg_rev < 0x0200))
> >  		otg_caps->adp_support = false;
> > +	if (of_find_property(np, "hcd-needs-companion", NULL))
> > +		otg_caps->needs_companion = true;
> 
> I'm not sure if otg_caps structure is a right place for this. Maybe Peter can confirm
> if this is OK or not.
> 
> I was thinking more about adding this bit in the otg_config structure.

I see. I also think the otg_config is more suitable.

> >
> >  	return 0;
> >  }
> > diff --git a/drivers/usb/common/usb-otg.c b/drivers/usb/common/usb-otg.c
> > index 41e762a..e0df839 100644
> > --- a/drivers/usb/common/usb-otg.c
> > +++ b/drivers/usb/common/usb-otg.c
> > @@ -823,13 +823,15 @@ int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum,
> >  	/* HCD will be started by OTG fsm when needed */
> >  	mutex_lock(&otg->fsm.lock);
> >  	if (otg->primary_hcd.hcd) {
> > -		/* probably a shared HCD ? */
> > -		if (usb_otg_hcd_is_primary_hcd(hcd)) {
> > +		/* probably a shared HCD or a companion OHCI HCD ? */
> > +		if (!otg->caps->needs_companion &&
> > +		    usb_otg_hcd_is_primary_hcd(hcd)) {
> >  			dev_err(otg_dev, "otg: primary host already registered\n");
> >  			goto err;
> >  		}
> >
> > -		if (hcd->shared_hcd == otg->primary_hcd.hcd) {
> > +		if (otg->caps->needs_companion ||
> > +		    (hcd->shared_hcd == otg->primary_hcd.hcd)) {
> >  			if (otg->shared_hcd.hcd) {
> >  				dev_err(otg_dev, "otg: shared host already registered\n");
> >  				goto err;
> > @@ -865,7 +867,8 @@ int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum,
> >  	 * we're ready only if we have shared HCD
> >  	 * or we don't need shared HCD.
> >  	 */
> > -	if (otg->shared_hcd.hcd || !otg->primary_hcd.hcd->shared_hcd) {
> > +	if (otg->shared_hcd.hcd || (!otg->caps->needs_companion &&
> > +				    !otg->primary_hcd.hcd->shared_hcd)) {
> >  		otg->host = hcd_to_bus(hcd);
> >  		/* FIXME: set bus->otg_port if this is true OTG port with HNP */
> >
> 
> These changes look good to me. Thanks.

Thank you for the comment.
If we change the "needs_companion" place to the otg_config,
do we need to add a flag into the otg, instead of otg->caps?

> > diff --git a/include/linux/usb/otg.h b/include/linux/usb/otg.h
> > index b094352..64a7db8 100644
> > --- a/include/linux/usb/otg.h
> > +++ b/include/linux/usb/otg.h
> > @@ -112,12 +112,14 @@ struct usb_otg {
> >   * @hnp_support: Indicates if the device supports HNP.
> >   * @srp_support: Indicates if the device supports SRP.
> >   * @adp_support: Indicates if the device supports ADP.
> > + * @needs_companion: Indicates if the device needs a companion controller.
> 
> Description is not exact. How about this.
> "Indicates if host controller needs a companion controller"
> 
> Is hcd_needs_companion is better than just needs_companion?

I agree with you.

So, I will modify my local patch and test it tomorrow.

Best regards,
Yoshihiro Shimoda

> 
> >   */
> >  struct usb_otg_caps {
> >  	u16 otg_rev;
> >  	bool hnp_support;
> >  	bool srp_support;
> >  	bool adp_support;
> > +	bool needs_companion;
> >  };
> >
> >  /**
> >
> 
> cheers,
> -roger