ALSA: usb-audio: work around streaming quirk for MacroSilicon MS2109

commit 1b7ecc241a67ad6b584e071bd791a54e0cd5f097 upstream.

Further investigation of the L-R swap problem on the MS2109 reveals that
the problem isn't that the channels are swapped, but rather that they
are swapped and also out of phase by one sample. In other words, the
issue is actually that the very first frame that comes from the hardware
is a half-frame containing only the right channel, and after that
everything becomes offset.

So introduce a new quirk field to drop the very first 2 bytes that come
in after the format is configured and a capture stream starts. This puts
the channels in phase and in the correct order.

Cc: stable@vger.kernel.org
Signed-off-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20200810082400.225858-1-marcan@marcan.st
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/usb/card.h b/sound/usb/card.h
index 71778ca4b26aafcb3dacedcc660947a5df61f7e2..b24f2efea1cb4785c70ef2936d16fde606958b84 100644 (file)
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -125,6 +125,7 @@ struct snd_usb_substream {
        unsigned int tx_length_quirk:1; /* add length specifier to transfers */
        unsigned int fmt_type;          /* USB audio format type (1-3) */
        unsigned int pkt_offset_adj;    /* Bytes to drop from beginning of packets (for non-compliant devices) */
+       unsigned int stream_offset_adj; /* Bytes to drop from beginning of stream (for non-compliant devices) */
 
        unsigned int running: 1;        /* running status */
 

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index f84c55ecd0fb404001232c3f3bec049fdcc32759..c97d9a537f763feb0d566258ff7d4ea68777ddc0 100644 (file)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1302,6 +1302,12 @@ static void retire_capture_urb(struct snd_usb_substream *subs,
                        // continue;
                }
                bytes = urb->iso_frame_desc[i].actual_length;
+               if (subs->stream_offset_adj > 0) {
+                       unsigned int adj = min(subs->stream_offset_adj, bytes);
+                       cp += adj;
+                       bytes -= adj;
+                       subs->stream_offset_adj -= adj;
+               }
                frames = bytes / stride;
                if (!subs->txfr_quirk)
                        bytes = frames * stride;

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 47979c9c3e2903ba856edac741bfc4e6c02c40d5..59529a9cab614e66088f6e6eabdfa74b6317c729 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1122,6 +1122,9 @@ void snd_usb_set_format_quirk(struct snd_usb_substream *subs,
        case USB_ID(0x041e, 0x3f19): /* E-Mu 0204 USB */
                set_format_emu_quirk(subs, fmt);
                break;
+       case USB_ID(0x534d, 0x2109): /* MacroSilicon MS2109 */
+               subs->stream_offset_adj = 2;
+               break;
        }
 }
 

diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 3b23102230c03d1558b0f067f963ccb0b5dfaaf4..1ffc32fd3a9eb4f74ab0f4bbaf050f5f213cc612 100644 (file)
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -95,6 +95,7 @@ static void snd_usb_init_substream(struct snd_usb_stream *as,
        subs->tx_length_quirk = as->chip->tx_length_quirk;
        subs->speed = snd_usb_get_speed(subs->dev);
        subs->pkt_offset_adj = 0;
+       subs->stream_offset_adj = 0;
 
        snd_usb_set_pcm_ops(as->pcm, stream);