diff options
Diffstat (limited to 'include/linux/usb/audio-v2.h')
| -rw-r--r-- | include/linux/usb/audio-v2.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/usb/audio-v2.h b/include/linux/usb/audio-v2.h index 716aebe339e8..964cb603f7c7 100644 --- a/include/linux/usb/audio-v2.h +++ b/include/linux/usb/audio-v2.h @@ -18,6 +18,21 @@ /* v1.0 and v2.0 of this standard have many things in common. For the rest * of the definitions, please refer to audio.h */ +/* + * bmControl field decoders + * + * From the USB Audio spec v2.0: + * + * bmaControls() is a (ch+1)-element array of 4-byte bitmaps, + * each containing a set of bit pairs. If a Control is present, + * it must be Host readable. If a certain Control is not + * present then the bit pair must be set to 0b00. + * If a Control is present but read-only, the bit pair must be + * set to 0b01. If a Control is also Host programmable, the bit + * pair must be set to 0b11. The value 0b10 is not allowed. + * + */ + static inline bool uac2_control_is_readable(u32 bmControls, u8 control) { return (bmControls >> (control * 2)) & 0x1; |