[PATCH v2] usb: core: new quirk to handle devices with zero configurations

[PATCH v2] usb: core: new quirk to handle devices with zero configurations

[Jie Deng]

Some USB devices incorrectly report bNumConfigurations as 0 in their
device descriptor, which causes the USB core to reject them during
enumeration.
logs:
usb 1-2: device descriptor read/64, error -71
usb 1-2: no configurations
usb 1-2: can't read configurations, error -22

However, these devices actually work correctly when
treated as having a single configuration.

Add a new quirk USB_QUIRK_FORCE_ONE_CONFIG to handle such devices.
When this quirk is set, assume the device has 1 configuration instead
of failing with -EINVAL.

This quirk is applied to the device with VID:PID 5131:2007 which
exhibits this behavior.

Signed-off-by: Jie Deng <dengjie03@kylinos.cn>
---

Changes in v2:
- Modify the sequence number of the quirks parameter
- Add the judgment condition of ncfg < 1
Link to v1: https://lore.kernel.org/linux-usb/
f7999b43-b6e2-44f4-b8e1-c2b5f5d04a5c@kylinos.cn/T/#mb5246d3b3e3bbb334c046bfa9a69b988f2d0688a
---
 Documentation/admin-guide/kernel-parameters.txt | 3 +++
 drivers/usb/core/config.c                       | 7 ++++++-
 drivers/usb/core/quirks.c                       | 5 +++++
 include/linux/usb/quirks.h                      | 3 +++
 4 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index cb850e5290c2..7d907efe9f49 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -8183,6 +8183,9 @@ Kernel parameters
 				p = USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT
 					(Reduce timeout of the SET_ADDRESS
 					request from 5000 ms to 500 ms);
+				q = USB_QUIRK_FORCE_ONE_CONFIG (Device
+					claims zero configurations,
+					forcing to 1);
 			Example: quirks=0781:5580:bk,0a5c:5834:gij
 
 	usbhid.mousepoll=
diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 1cd5fa61dc76..832717549515 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -927,7 +927,12 @@ int usb_get_configuration(struct usb_device *dev)
 		dev->descriptor.bNumConfigurations = ncfg = USB_MAXCONFIG;
 	}
 
-	if (ncfg < 1) {
+	if (ncfg < 1 && dev->quirks & USB_QUIRK_FORCE_ONE_CONFIG) {
+		dev_info(ddev, "Device claims zero configurations, "
+				"forcing to 1\n");
+		dev->descriptor.bNumConfigurations = 1;
+		ncfg = 1;
+	} else if (ncfg < 1) {
 		dev_err(ddev, "no configurations\n");
 		return -EINVAL;
 	}
diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index e347236d83e8..7bd408db05f4 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -140,6 +140,8 @@ static int quirks_param_set(const char *value, const struct kernel_param *kp)
 			case 'p':
 				flags |= USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT;
 				break;
+			case 'q':
+				flags |= USB_QUIRK_FORCE_ONE_CONFIG;
 			/* Ignore unrecognized flag characters */
 			}
 		}
@@ -589,6 +591,9 @@ static const struct usb_device_id usb_quirk_list[] = {
 	/* VCOM device */
 	{ USB_DEVICE(0x4296, 0x7570), .driver_info = USB_QUIRK_CONFIG_INTF_STRINGS },
 
+	/* Noji-MCS SmartCard Reader */
+	{ USB_DEVICE(0x5131, 0x2007), .driver_info = USB_QUIRK_FORCE_ONE_CONFIG },
+
 	/* INTEL VALUE SSD */
 	{ USB_DEVICE(0x8086, 0xf1a5), .driver_info = USB_QUIRK_RESET_RESUME },
 
diff --git a/include/linux/usb/quirks.h b/include/linux/usb/quirks.h
index 2f7bd2fdc616..b3cc7beab4a3 100644
--- a/include/linux/usb/quirks.h
+++ b/include/linux/usb/quirks.h
@@ -78,4 +78,7 @@
 /* skip BOS descriptor request */
 #define USB_QUIRK_NO_BOS			BIT(17)
 
+/* Device claims zero configurations, forcing to 1 */
+#define USB_QUIRK_FORCE_ONE_CONFIG		BIT(18)
+
 #endif /* __LINUX_USB_QUIRKS_H */
-- 
2.25.1

Re: [PATCH v2] usb: core: new quirk to handle devices with zero configurations

[Greg Kroah-Hartman]

On Fri, Feb 27, 2026 at 02:04:00PM +0800, Jie Deng wrote:
> Some USB devices incorrectly report bNumConfigurations as 0 in their
> device descriptor, which causes the USB core to reject them during
> enumeration.
> logs:
> usb 1-2: device descriptor read/64, error -71
> usb 1-2: no configurations
> usb 1-2: can't read configurations, error -22
> 
> However, these devices actually work correctly when
> treated as having a single configuration.
> 
> Add a new quirk USB_QUIRK_FORCE_ONE_CONFIG to handle such devices.
> When this quirk is set, assume the device has 1 configuration instead
> of failing with -EINVAL.
> 
> This quirk is applied to the device with VID:PID 5131:2007 which
> exhibits this behavior.
> 
> Signed-off-by: Jie Deng <dengjie03@kylinos.cn>
> ---
> 
> Changes in v2:
> - Modify the sequence number of the quirks parameter
> - Add the judgment condition of ncfg < 1
> Link to v1: https://lore.kernel.org/linux-usb/
> f7999b43-b6e2-44f4-b8e1-c2b5f5d04a5c@kylinos.cn/T/#mb5246d3b3e3bbb334c046bfa9a69b988f2d0688a
> ---
>  Documentation/admin-guide/kernel-parameters.txt | 3 +++
>  drivers/usb/core/config.c                       | 7 ++++++-
>  drivers/usb/core/quirks.c                       | 5 +++++
>  include/linux/usb/quirks.h                      | 3 +++
>  4 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index cb850e5290c2..7d907efe9f49 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -8183,6 +8183,9 @@ Kernel parameters
>  				p = USB_QUIRK_SHORT_SET_ADDRESS_REQ_TIMEOUT
>  					(Reduce timeout of the SET_ADDRESS
>  					request from 5000 ms to 500 ms);
> +				q = USB_QUIRK_FORCE_ONE_CONFIG (Device
> +					claims zero configurations,
> +					forcing to 1);
>  			Example: quirks=0781:5580:bk,0a5c:5834:gij
>  
>  	usbhid.mousepoll=
> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
> index 1cd5fa61dc76..832717549515 100644
> --- a/drivers/usb/core/config.c
> +++ b/drivers/usb/core/config.c
> @@ -927,7 +927,12 @@ int usb_get_configuration(struct usb_device *dev)
>  		dev->descriptor.bNumConfigurations = ncfg = USB_MAXCONFIG;
>  	}
>  
> -	if (ncfg < 1) {
> +	if (ncfg < 1 && dev->quirks & USB_QUIRK_FORCE_ONE_CONFIG) {
> +		dev_info(ddev, "Device claims zero configurations, "
> +				"forcing to 1\n");

Do not break a string like this, make it all one line please.
checkpatch should have warned you about this?

thanks,

greg k-h

Re: [PATCH v2] usb: core: new quirk to handle devices with zero configurations

[Jie Deng]

在 2026/2/27 14:06, Greg Kroah-Hartman 写道:
> On Fri, Feb 27, 2026 at 02:04:00PM +0800, Jie Deng wrote:
>> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
>> index 1cd5fa61dc76..832717549515 100644
>> --- a/drivers/usb/core/config.c
>> +++ b/drivers/usb/core/config.c
>> @@ -927,7 +927,12 @@ int usb_get_configuration(struct usb_device *dev)
>>   		dev->descriptor.bNumConfigurations = ncfg = USB_MAXCONFIG;
>>   	}
>>   
>> -	if (ncfg < 1) {
>> +	if (ncfg < 1 && dev->quirks & USB_QUIRK_FORCE_ONE_CONFIG) {
>> +		dev_info(ddev, "Device claims zero configurations, "
>> +				"forcing to 1\n");
> Do not break a string like this, make it all one line please.
> checkpatch should have warned you about this?
>
> thanks,
>
> greg k-h

Thank you for your reply. I will make the necessary revisions and submit 
the updated patch.

Jie Deng