The Longmai Technologies USB Key (0x04b4:0xb708) advertises itself as a
SCSI/Bulk-only mass storage device but does not correctly handle ATA
pass-through commands. When such a command (ATA_12 or ATA_16) is sent to
the device it fails to respond and the transfer eventually times out,
leaving the device unusable.

Add an unusual_devs entry for this device that sets the US_FL_NO_ATA_1X
flag, so usb-storage short-circuits ATA pass-through commands and returns
INVALID COMMAND OPERATION CODE (0x20 0x05 0x24 0x00) instead of forwarding
them to the device.

Information about the device in /sys/kernel/debug/usb/devices:

T:  Bus=02 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#= 12 Spd=480  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=06 Prot=50 MxPS=64 #Cfgs=  1
P:  Vendor=04b4 ProdID=b708 Rev= 1.00
S:  Manufacturer=Longmai Technologies
S:  Product=USB Key
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

Reported-by: Ai Chao <aichao@kylinos.cn>
Signed-off-by: Huang Wei <huangwei@kylinos.cn>
---
 drivers/usb/storage/unusual_devs.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
index cb03d3615614..ef77ab6fd42f 100644
--- a/drivers/usb/storage/unusual_devs.h
+++ b/drivers/usb/storage/unusual_devs.h
@@ -2379,6 +2379,13 @@ UNUSUAL_DEV( 0xed10, 0x7636, 0x0001, 0x0001,
 		"Digital MP3 Audio Player",
 		USB_SC_DEVICE, USB_PR_DEVICE, NULL, US_FL_NOT_LOCKABLE ),
 
+/* Reported by Ai Chao <aichao@kylinos.cn> */
+UNUSUAL_DEV(  0x04b4, 0xb708, 0x0000, 0xffff,
+		"Longmai Technologies",
+		"USB Key",
+		USB_SC_SCSI, USB_PR_BULK, NULL,
+		US_FL_NO_ATA_1X),
+
 /* Unusual uas devices */
 #if IS_ENABLED(CONFIG_USB_UAS)
 #include "unusual_uas.h"
-- 
2.25.1

On Wed, Jul 15, 2026 at 04:45:30PM +0800, Huang Wei wrote:
> The Longmai Technologies USB Key (0x04b4:0xb708) advertises itself as a
> SCSI/Bulk-only mass storage device but does not correctly handle ATA
> pass-through commands. When such a command (ATA_12 or ATA_16) is sent to
> the device it fails to respond and the transfer eventually times out,
> leaving the device unusable.
> 
> Add an unusual_devs entry for this device that sets the US_FL_NO_ATA_1X
> flag, so usb-storage short-circuits ATA pass-through commands and returns
> INVALID COMMAND OPERATION CODE (0x20 0x05 0x24 0x00) instead of forwarding
> them to the device.
> 
> Information about the device in /sys/kernel/debug/usb/devices:
> 
> T:  Bus=02 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#= 12 Spd=480  MxCh= 0
> D:  Ver= 2.00 Cls=00(>ifc ) Sub=06 Prot=50 MxPS=64 #Cfgs=  1
> P:  Vendor=04b4 ProdID=b708 Rev= 1.00
> S:  Manufacturer=Longmai Technologies
> S:  Product=USB Key
> C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
> I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
> 
> Reported-by: Ai Chao <aichao@kylinos.cn>
> Signed-off-by: Huang Wei <huangwei@kylinos.cn>
> ---
>  drivers/usb/storage/unusual_devs.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
> index cb03d3615614..ef77ab6fd42f 100644
> --- a/drivers/usb/storage/unusual_devs.h
> +++ b/drivers/usb/storage/unusual_devs.h
> @@ -2379,6 +2379,13 @@ UNUSUAL_DEV( 0xed10, 0x7636, 0x0001, 0x0001,
>  		"Digital MP3 Audio Player",
>  		USB_SC_DEVICE, USB_PR_DEVICE, NULL, US_FL_NOT_LOCKABLE ),
>  
> +/* Reported by Ai Chao <aichao@kylinos.cn> */
> +UNUSUAL_DEV(  0x04b4, 0xb708, 0x0000, 0xffff,
> +		"Longmai Technologies",
> +		"USB Key",
> +		USB_SC_SCSI, USB_PR_BULK, NULL,
> +		US_FL_NO_ATA_1X),
> +

According to the comments at the start of the file, entries should be 
sorted by VendorID, then ProductID.

Alan Stern

>  /* Unusual uas devices */
>  #if IS_ENABLED(CONFIG_USB_UAS)
>  #include "unusual_uas.h"
> -- 
> 2.25.1