path: root/sound/usb/usbaudio.h
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authorTakashi Iwai <tiwai@suse.de>2021-04-14 10:32:55 +0200
committerTakashi Iwai <tiwai@suse.de>2021-04-14 14:24:22 +0200
commitebe8dc5afb3912e2d4f5c62cf7c492a13143a77a (patch)
tree6bc1eb3e80c598688df4c4a3d7610fcb267ed578 /sound/usb/usbaudio.h
parentALSA: control_led - fix the stack usage (control element ops) (diff)
ALSA: usb-audio: Apply implicit feedback mode for BOSS devices
During the recent rewrite of the implicit feedback support, we've tested to apply the implicit fb on BOSS devices, but it failed, as the capture stream didn't start without the playback. As the end result, it got another type of quirk for tying both streams but starts playback always (commit 6234fdc1cede "ALSA: usb-audio: Quirk for BOSS GT-001"). Meanwhile, Mike Oliphant has tested the real implicit feedback mode for the playback again with the latest code, and found out that it actually works if the initial feedback sync is skipped; that is, on those BOSS devices, the playback stream has to be started at first without waiting for the capture URB completions. Otherwise it gets stuck. In the rest operations after the capture stream processed, we can take them as the implicit feedback source. This patch is an attempt to improve the support for BOSS devices with the implicit feedback mode in the way described above. It adds a new flag to snd_usb_audio, playback_first, indicating that the playback stream starts without sync with the initial capture completion. This flag is set in the quirk table with the new IMPLICIT_FB_BOTH type. Reported-and-tested-by: Mike Oliphant <oliphant@nostatic.org> Link: https://lore.kernel.org/r/20210414083255.9527-1-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb/usbaudio.h')
1 files changed, 1 insertions, 0 deletions
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index a536ee33d36e..538831cbd925 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -37,6 +37,7 @@ struct snd_usb_audio {
unsigned int txfr_quirk:1; /* Subframe boundaries on transfers */
unsigned int tx_length_quirk:1; /* Put length specifier in transfers */
unsigned int need_delayed_register:1; /* warn for delayed registration */
+ unsigned int playback_first:1; /* for implicit fb: don't wait for the first capture URBs */
int num_interfaces;
int num_suspended_intf;
int sample_rate_read_error;