Re: [PATCH 5/5] usb: dwc3: rockchip: fix USB-C reconnect in gadget mode

From: Igor Paunovic <royalnet026@gmail.com>
To: Sebastian Reichel <sebastian.reichel@collabora.com>
Cc: Igor Paunovic <royalnet026@gmail.com>,
	Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Heiko Stuebner <heiko@sntech.de>, Vinod Koul <vkoul@kernel.org>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Manivannan Sadhasivam <mani@kernel.org>,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org,
	linux-phy@lists.infradead.org, kernel@collabora.com
Subject: Re: [PATCH 5/5] usb: dwc3: rockchip: fix USB-C reconnect in gadget mode
Date: Fri, 18 Sep 2026 11:10:32 +0200	[thread overview]
Message-ID: <20260918091032.15593-1-royalnet026@gmail.com> (raw)
In-Reply-To: <20260915-b4-rockchip-dwc3-rockchip-glue-v1-5-763bb546824e@collabora.com>

Hi Sebastian,

With this patch applied, the series fails to build when dwc3 is
host-only and USB_GADGET is either disabled, or a module while the
glue is built in. I built it on top of v7.3-rc1 for arm64 (allnoconfig
plus a fragment, gcc 13.3) with USB=y, USB_DWC3=y, USB_DWC3_HOST=y,
USB_DWC3_ROCKCHIP=y and USB_GADGET unset:

  aarch64-linux-gnu-ld: drivers/usb/dwc3/dwc3-rockchip.o: in function `dwc3_rockchip_set_role':
  dwc3-rockchip.c:(.text+0x270): undefined reference to `usb_udc_vbus_handler'

With USB_DWC3=m and USB_DWC3_ROCKCHIP=m, modpost reports
usb_udc_vbus_handler as undefined. With USB_GADGET=m and the glue
built in, the link error is the same. With patches 1-4 only, all
three configs build.

dwc3_rockchip_vbus_handler() checks dwc->gadget only at runtime, so
the call to usb_udc_vbus_handler() is always compiled in. That
function is only built with USB_GADGET (drivers/usb/gadget/udc/core.c)
and has no stub in include/linux/usb/gadget.h, and USB_DWC3_ROCKCHIP
does not depend on the gadget side.

The same test run also shows that the two EXPORT_TRACEPOINT_SYMBOL_GPL
lines in 4/5 fix the modpost error I reported on v14. With them
dropped, dwc3=y/glue=m (the v14 case) and dwc3=m/glue=m, both with
tracing, fail with the same four undefined tracepoint symbols.

This was a build test only; I did not run anything on a board. An LLM
assistant wrote the build script and helped draft this mail.

Igor

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