Re: [PATCH] usb: dwc2: handle OTG HNP SetFeature requests

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Aug 26, 2026 at 03:07:50AM +0000, NG, TZE YEE wrote:
> On 17/8/2026 4:00 pm, NG, TZE YEE wrote:
> > From: Adrian Ng Ho Yin <adrian.ho.yin.ng@altera.com>
> > 
> > Without handling for b_hnp_enable, a_hnp_support, and a_alt_hnp_support,
> > HNP cannot be enabled when two OTG controllers are connected.
> > 
> > Handle SetFeature for these OTG selectors, gated on otg_caps.hnp_support.
> > The OTG specification only defines SetFeature for them, so reject
> > ClearFeature with -EINVAL instead of silently accepting it. Use dev_dbg
> > for status updates to avoid noisy logs.
> > 
> > Advertise the core's HNP/SRP capability during gadget init by restoring
> > GUSBCFG_HNPCAP/SRPCAP from otg_caps, mirroring dwc2_gusbcfg_init() on the
> > host side, instead of clearing them unconditionally.
> > 
> > Clear the HNP flags and GOTGCTL_DEVHNPEN on disconnect/reset so OTG state
> > does not leak across sessions.
> > 
> > Signed-off-by: Adrian Ng Ho Yin <adrian.ho.yin.ng@altera.com>
> > Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
> > ---
> >   drivers/usb/dwc2/gadget.c | 51 +++++++++++++++++++++++++++++++++++++--
> >   1 file changed, 49 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> > index c8b02c27d27d..4d905989c09f 100644
> > --- a/drivers/usb/dwc2/gadget.c
> > +++ b/drivers/usb/dwc2/gadget.c
> > @@ -1780,6 +1780,7 @@ static int dwc2_hsotg_process_req_feature(struct dwc2_hsotg *hsotg,
> >   	struct dwc2_hsotg_ep *ep;
> >   	int ret;
> >   	bool halted;
> > +	u32 otgctl;
> >   	u32 recip;
> >   	u32 wValue;
> >   	u32 wIndex;
> > @@ -1809,6 +1810,36 @@ static int dwc2_hsotg_process_req_feature(struct dwc2_hsotg *hsotg,
> >   
> >   			hsotg->test_mode = wIndex >> 8;
> >   			break;
> > +		case USB_DEVICE_B_HNP_ENABLE:
> > +			if (!hsotg->params.otg_caps.hnp_support)
> > +				return -ENOENT;
> > +			if (!set)
> > +				return -EINVAL;
> > +
> > +			otgctl = dwc2_readl(hsotg, GOTGCTL);
> > +			otgctl |= GOTGCTL_DEVHNPEN;
> > +			dwc2_writel(hsotg, otgctl, GOTGCTL);
> > +			hsotg->gadget.b_hnp_enable = 1;
> > +			dev_dbg(hsotg->dev, "HNP enabled\n");
> > +			break;
> > +		case USB_DEVICE_A_HNP_SUPPORT:
> > +			if (!hsotg->params.otg_caps.hnp_support)
> > +				return -ENOENT;
> > +			if (!set)
> > +				return -EINVAL;
> > +
> > +			hsotg->gadget.a_hnp_support = 1;
> > +			dev_dbg(hsotg->dev, "a_hnp_support set\n");
> > +			break;
> > +		case USB_DEVICE_A_ALT_HNP_SUPPORT:
> > +			if (!hsotg->params.otg_caps.hnp_support)
> > +				return -ENOENT;
> > +			if (!set)
> > +				return -EINVAL;
> > +
> > +			hsotg->gadget.a_alt_hnp_support = 1;
> > +			dev_dbg(hsotg->dev, "a_alt_hnp_support set\n");
> > +			break;
> >   		default:
> >   			return -ENOENT;
> >   		}
> > @@ -3322,6 +3353,13 @@ void dwc2_hsotg_disconnect(struct dwc2_hsotg *hsotg)
> >   	hsotg->connected = 0;
> >   	hsotg->test_mode = 0;
> >   
> > +	if (hsotg->params.otg_caps.hnp_support) {
> > +		hsotg->gadget.b_hnp_enable = 0;
> > +		hsotg->gadget.a_hnp_support = 0;
> > +		hsotg->gadget.a_alt_hnp_support = 0;
> > +		dwc2_clear_bit(hsotg, GOTGCTL, GOTGCTL_DEVHNPEN);
> > +	}
> > +
> >   	/* all endpoints should be shutdown */
> >   	for (ep = 0; ep < hsotg->num_of_eps; ep++) {
> >   		if (hsotg->eps_in[ep])
> > @@ -3416,9 +3454,18 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
> >   	usbcfg &= ~GUSBCFG_TOUTCAL_MASK;
> >   	usbcfg |= GUSBCFG_TOUTCAL(7);
> >   
> > -	/* remove the HNP/SRP and set the PHY */
> > +	/*
> > +	 * Configure HNP/SRP capability from params (same idea as
> > +	 * dwc2_gusbcfg_init() for host). Unconditionally clearing these
> > +	 * bits leaves an HNP-capable OTG gadget unable to negotiate.
> > +	 */
> >   	usbcfg &= ~(GUSBCFG_SRPCAP | GUSBCFG_HNPCAP);
> > -        dwc2_writel(hsotg, usbcfg, GUSBCFG);
> > +	if (hsotg->params.otg_caps.hnp_support &&
> > +	    hsotg->params.otg_caps.srp_support)
> > +		usbcfg |= GUSBCFG_HNPCAP;
> > +	if (hsotg->params.otg_caps.srp_support)
> > +		usbcfg |= GUSBCFG_SRPCAP;
> > +	dwc2_writel(hsotg, usbcfg, GUSBCFG);
> >   
> >   	dwc2_phy_init(hsotg, true);
> >
> 
> Hi,
> 
> Gentle ping on this patch. It has been over a week with no feedback.

It's the middle of the merge window, nothing can happen with new patches
until -rc1 is out.  If you wish to make the review process go faster,
please help review other pending patches on the list.

thanks,

greg k-h