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| author | Andreas Pape <apape@de.adit-jv.com> | 2016-12-06 14:46:14 +0900 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2016-12-06 13:55:59 +0100 |
| commit | fd1a5059610cd3887f1050171a840ca864108730 (patch) | |
| tree | 749a58c5972b72aec1a78c765f2f9cf4b3e1a776 /sound/usb | |
| parent | 1e2e3fe480064ca33186e5a923beaa160efed35d (diff) | |
| download | linux-fd1a5059610cd3887f1050171a840ca864108730.tar.bz2 | |
ALSA: usb-audio: more tolerant packetsize
since commit 57e6dae1087b ("ALSA: usb-audio: do not trust too-big
wMaxPacketSize values"), the expected packetsize is always limited
to nominal + 25%. It was discovered, that some devices (Android audio
accessory) have a much higher jitter in used packetsizes than 25%
which would result in BABBLE condition and dropping of packets.
A better solution is so assume the jitter to be the nominal packetsize:
-one nearly empty packet followed by a almost 150% sized one.
V2: changed to assume max frequency is +50 of nominal packetsize.
Signed-off-by: Andreas Pape <apape@de.adit-jv.com>
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb')
| -rw-r--r-- | sound/usb/endpoint.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index c470251cea4b..a2931f49a1fc 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -632,8 +632,8 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep, ep->stride = frame_bits >> 3; ep->silence_value = pcm_format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0; - /* assume max. frequency is 25% higher than nominal */ - ep->freqmax = ep->freqn + (ep->freqn >> 2); + /* assume max. frequency is 50% higher than nominal */ + ep->freqmax = ep->freqn + (ep->freqn >> 1); /* Round up freqmax to nearest integer in order to calculate maximum * packet size, which must represent a whole number of frames. * This is accomplished by adding 0x0.ffff before converting the |