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| author | Daniel Mack <daniel@caiaq.de> | 2010-06-16 19:57:30 +0400 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2010-06-23 18:09:50 +0400 |
| commit | 157a57b6fae7d3c6d24b7623dcc6679c6d244621 (patch) | |
| tree | d4e803455aa7cbcab244355171be428a3b33fa47 /include/linux/usb/audio-v2.h | |
| parent | 21af7d8c0c0a88f6f9fc6993d73001b4caf23b08 (diff) | |
| download | linux-157a57b6fae7d3c6d24b7623dcc6679c6d244621.tar.xz | |
ALSA: usb-audio: move and add some comments
Also add a list of open topics.
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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; |