Also add a list of open topics.
Signed-off-by: Daniel Mack daniel@caiaq.de --- include/linux/usb/audio-v2.h | 15 +++++++++++++++ sound/usb/clock.c | 16 ++++++++++++++-- sound/usb/mixer.c | 24 ++++++++++++++++-------- 3 files changed, 45 insertions(+), 10 deletions(-)
diff --git a/include/linux/usb/audio-v2.h b/include/linux/usb/audio-v2.h index 716aebe..964cb60 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; diff --git a/sound/usb/clock.c b/sound/usb/clock.c index 386b09c..7279d61 100644 --- a/sound/usb/clock.c +++ b/sound/usb/clock.c @@ -120,8 +120,6 @@ static bool uac_clock_source_is_valid(struct snd_usb_audio *chip, int source_id) return !!data; }
-/* Try to find the clock source ID of a given clock entity */ - static int __uac_clock_find_source(struct snd_usb_audio *chip, struct usb_host_interface *host_iface, int entity_id, unsigned long *visited) @@ -154,6 +152,8 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip, if (ret < 0) return ret;
+ /* Selector values are one-based */ + if (ret > selector->bNrInPins || ret < 1) { printk(KERN_ERR "%s(): selector reported illegal value, id %d, ret %d\n", @@ -176,6 +176,17 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip, return -EINVAL; }
+/* + * For all kinds of sample rate settings and other device queries, + * the clock source (end-leaf) must be used. However, clock selectors, + * clock multipliers and sample rate converters may be specified as + * clock source input to terminal. This functions walks the clock path + * to its end and tries to find the source. + * + * The 'visited' bitfield is used internally to detect recursive loops. + * + * Returns the clock source UnitID (>=0) on success, or an error. + */ int snd_usb_clock_find_source(struct snd_usb_audio *chip, struct usb_host_interface *host_iface, int entity_id) @@ -246,6 +257,7 @@ static int set_sample_rate_v2(struct snd_usb_audio *chip, int iface, return clock;
if (!uac_clock_source_is_valid(chip, clock)) { + /* TODO: should we try to find valid clock setups by ourself? */ snd_printk(KERN_ERR "%d:%d:%d: clock source %d is not valid, cannot use\n", dev->devnum, iface, fmt->altsetting, clock); return -ENXIO; diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index b6a261f..7ffea71 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -26,6 +26,22 @@ * */
+/* + * TODOs, for both the mixer and the streaming interfaces: + * + * - support for UAC2 effect units + * - support for graphical equalizers + * - RANGE and MEM set commands (UAC2) + * - RANGE and MEM interrupt dispatchers (UAC2) + * - audio channel clustering (UAC2) + * - audio sample rate converter units (UAC2) + * - proper handling of clock multipliers (UAC2) + * - dispatch clock change notifications (UAC2) + * - stop PCM streams which use a clock that became invalid + * - stop PCM streams which use a clock selector that has changed + * - parse available sample rates again when clock sources changed + */ + #include <linux/bitops.h> #include <linux/init.h> #include <linux/list.h> @@ -1186,14 +1202,6 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void } } else { /* UAC_VERSION_2 */ for (i = 0; i < 30/2; i++) { - /* 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. */ unsigned int ch_bits = 0; unsigned int ch_read_only = 0;