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 ed87cc83eb47dab3134ac1a673f257c643d739a8..0cde519bfa4207a34eeb23cbc4cb85468915b754 100644 (file)
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -126,6 +126,7 @@ 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 ff38fca1781b6ef30fce456d15dae594db920295..f27213b846e6b655c861bd21298619a0a8ce8437 100644 (file)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1313,6 +1313,12 @@ 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 cd36394e27ae60c56ac6e18f3a1acc35ef2414ff..4f4dc43e56a7b36566ad9bef0dd27f91428d4c90 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1120,6 +1120,9 @@ 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 d1776e5517ffee4687c1200fff51cb3fb52fbf2a..452646959586eb839220112ebe723d5629c05f43 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);