Re: Associate physical device with device name

[Jimmy Assarsson <extja@kvaser.com>]

On 2018-02-09 11:47, Marc Kleine-Budde wrote:
> On 02/08/2018 02:04 PM, Jimmy Assarsson wrote:
>> No, they are not identical. The EAN and serial number is stored on the
>> device.
> 
> How to read them?

It is part of the "kvaser_msg_cardinfo" command, see
https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git/tree/drivers/net/can/usb/kvaser_usb.c#n198

>> Which makes a single device unique. It is possible to fetch these
>> from the device. And same applies to all Kvaser CAN interfaces,
>> regardless if they are connected via USB, PCI-express or ethernet.
> What's the output of the udev when using the proper path to your device?
> 
> "udevadm info --path=/devices/pci0000:00/0000:00:14.0/usb1/1-2/ -a"

All devices with the same EAN look identical, since we do not set serial
number in the USB descriptor.

The output from "udevadm info 
--path=/sys/devices/pci0000:00/0000:00:02.1/usb1/1-4/1-4.1/1-4.1:1.0 -a"

   looking at device 
'/devices/pci0000:00/0000:00:02.1/usb1/1-4/1-4.1/1-4.1:1.0':
     KERNEL=="1-4.1:1.0"
     SUBSYSTEM=="usb"
     DRIVER=="kvaser_usb"
     ATTR{authorized}=="1"
     ATTR{bAlternateSetting}==" 0"
     ATTR{bInterfaceClass}=="00"
     ATTR{bInterfaceNumber}=="00"
     ATTR{bInterfaceProtocol}=="00"
     ATTR{bInterfaceSubClass}=="00"
     ATTR{bNumEndpoints}=="02"
     ATTR{supports_autosuspend}=="0"

   looking at parent device 
'/devices/pci0000:00/0000:00:02.1/usb1/1-4/1-4.1':
     KERNELS=="1-4.1"
     SUBSYSTEMS=="usb"
     DRIVERS=="usb"
     ATTRS{authorized}=="1"
     ATTRS{avoid_reset_quirk}=="0"
     ATTRS{bConfigurationValue}=="1"
     ATTRS{bDeviceClass}=="ff"
     ATTRS{bDeviceProtocol}=="00"
     ATTRS{bDeviceSubClass}=="00"
     ATTRS{bMaxPacketSize0}=="64"
     ATTRS{bMaxPower}=="132mA"
     ATTRS{bNumConfigurations}=="1"
     ATTRS{bNumInterfaces}==" 1"
     ATTRS{bcdDevice}=="0001"
     ATTRS{bmAttributes}=="c0"
     ATTRS{busnum}=="1"
     ATTRS{configuration}==""
     ATTRS{devnum}=="26"
     ATTRS{devpath}=="4.1"
     ATTRS{idProduct}=="0123"
     ATTRS{idVendor}=="0bfd"
     ATTRS{ltm_capable}=="no"
     ATTRS{manufacturer}=="Kvaser AB"
     ATTRS{maxchild}=="0"
     ATTRS{product}=="Kvaser USBcan Light"
     ATTRS{quirks}=="0x0"
     ATTRS{removable}=="unknown"
     ATTRS{speed}=="480"
     ATTRS{urbnum}=="17"
     ATTRS{version}==" 2.00"