expose device name and bus info

[bazile-clyde]

From the kernel docs here

[card] Name of the device, a NUL-terminated UTF-8 string. For example: “Yoyodyne TV/FM”. One driver may support different brands or models of video hardware. This information is intended for users, for example in a menu of available devices. Since multiple TV cards of the same brand may be installed which are supported by the same driver, this name should be combined with the character device file name (e. g. /dev/video2) or the bus_info string to avoid ambiguities.

[bus_info] Location of the device in the system, a NUL-terminated ASCII string. For example: “PCI:0000:05:06.0”. This information is intended for users, to distinguish multiple identical devices. If no such information is available the field must simply count the devices controlled by the driver (“platform:vivi-000”). The bus_info must start with “PCI:” for PCI boards, “PCIe:” for PCI Express boards, “usb-” for USB devices, “I2C:” for i2c devices, “ISA:” for ISA devices, “parport” for parallel port devices and “platform:” for platform devices.

[bazile-clyde]

nit: this already done above.

[edaniels]

should this have a better name in this case? Like path or something? the syscall side is fine but this file is an opportunity for cleaner names

[bazile-clyde]

No. See the comment attached to this PR. In short, we use GetName to get the human-readable name. For conflicts the kernel recommends you append either the bus info or the path. The bus info isn't exposed so I exposed it here. The path isn't in the v4l2_capability struct so we can't "expose" it. We already know what it is because we've used it (or a symbolic link to it) to open the device. How this will ultimately be displayed by the user is up to the caller. They'll most likely do one of the following

• Yoyodyne TV/FM if no conflicts
• Yoyodyne TV/FM (PCI:0000:05:06.0) in the case of conflicts OR
• Yoyodyne TV/FM (/dev/video2) in the case of conflicts

[edaniels]

Got it. Makes sense.

[edaniels]

LGTM