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[176.198.166.64]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42f7d2226d0sm17468392f8f.21.2025.12.06.17.21.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 06 Dec 2025 17:21:16 -0800 (PST) From: =?UTF-8?q?Johannes=20Br=C3=BCderl?= To: linux-usb@vger.kernel.org Cc: gregkh@linuxfoundation.org, =?UTF-8?q?Johannes=20Br=C3=BCderl?= Subject: [PATCH v2] usb: core: add USB_QUIRK_NO_BOS for devices that hang on BOS descriptor Date: Sun, 7 Dec 2025 02:20:59 +0100 Message-ID: <20251207012059.7899-1-johannes.bruederl@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <2025120708-header-startling-ffaf@gregkh> References: <2025120708-header-startling-ffaf@gregkh> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add USB_QUIRK_NO_BOS quirk flag to skip requesting the BOS descriptor for devices that cannot handle it. Add Elgato 4K X (0fd9:009b) to the quirk table. This device hangs when the BOS descriptor is requested at SuperSpeed Plus (10Gbps). Link: https://bugzilla.kernel.org/show_bug.cgi?id=220027 Signed-off-by: Johannes Brüderl --- v2: Return -ENOMSG instead of 0 to properly indicate no BOS data. Tested unbind/rebind via /sys/bus/usb/drivers/usb/unbind - works correctly. Userspace tools (lsusb) handle missing BOS gracefully (no BOS section shown). Before (device hangs at SuperSpeed Plus, then re-enumerates at lower speed with different product ID 009c): [ 3.284990] usb 2-2: new SuperSpeed Plus Gen 2x1 USB device number 2 using xhci_hcd [ 8.574542] usb 2-2: unable to get BOS descriptor or descriptor too short [ 8.600018] usb 2-2: unable to read config index 0 descriptor/start: -71 [ 8.600027] usb 2-2: can't read configurations, error -71 [ 8.998412] usb 2-2: Device not responding to setup address. [ 9.215157] usb 2-2: Device not responding to setup address. [ 9.422737] usb 2-2: device not accepting address 3, error -71 [ 10.990897] usb 2-2: new SuperSpeed USB device number 5 using xhci_hcd [ 11.065869] usb 2-2: LPM exit latency is zeroed, disabling LPM. [ 11.152244] usb 2-2: New USB device found, idVendor=0fd9, idProduct=009c After (device enumerates correctly at SuperSpeed Plus): [ 3.297159] usb 2-2: new SuperSpeed Plus Gen 2x1 USB device number 2 using xhci_hcd [ 3.354248] usb 2-2: skipping BOS descriptor [ 3.432917] usb 2-2: New USB device found, idVendor=0fd9, idProduct=009b [ 3.432927] usb 2-2: Product: Elgato 4K X lsusb -t output: /: Bus 002.Port 001: Dev 001, Class=root_hub, Driver=xhci_hcd/4p, 10000M |__ Port 002: Dev 003, If 0, Class=Video, Driver=uvcvideo, 10000M drivers/usb/core/config.c | 5 +++++ drivers/usb/core/quirks.c | 3 +++ include/linux/usb/quirks.h | 3 +++ 3 files changed, 11 insertions(+) diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c index baf5bc844b6f..2bb1ceb9d621 100644 --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -1040,6 +1040,11 @@ int usb_get_bos_descriptor(struct usb_device *dev) __u8 cap_type; int ret; + if (dev->quirks & USB_QUIRK_NO_BOS) { + dev_dbg(ddev, "skipping BOS descriptor\n"); + return -ENOMSG; + } + bos = kzalloc(sizeof(*bos), GFP_KERNEL); if (!bos) return -ENOMEM; diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c index 47f589c4104a..69ec914e5f45 100644 --- a/drivers/usb/core/quirks.c +++ b/drivers/usb/core/quirks.c @@ -581,6 +581,9 @@ static const struct usb_device_id usb_quirk_list[] = { /* INTEL VALUE SSD */ { USB_DEVICE(0x8086, 0xf1a5), .driver_info = USB_QUIRK_RESET_RESUME }, + /* Elgato 4K X - BOS descriptor fetch hangs at SuperSpeed Plus */ + { USB_DEVICE(0x0fd9, 0x009b), .driver_info = USB_QUIRK_NO_BOS }, + { } /* terminating entry must be last */ }; diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h index 59409c1fc3de..2f7bd2fdc616 100644 --- a/include/linux/usb/quirks.h +++ b/include/linux/usb/quirks.h @@ -75,4 +75,7 @@ /* short SET_ADDRESS request timeout */ #define USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT BIT(16) +/* skip BOS descriptor request */ +#define USB_QUIRK_NO_BOS BIT(17) + #endif /* __LINUX_USB_QUIRKS_H */ -- 2.52.0