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 f39f23e3525df1c520dc87d12592dcbd8a8b3eea..d8ec5caf464dea21db0b715be57b0137d478bb73 100644 (file)
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -133,6 +133,7 @@ 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 0247162a9fbf3498c0f471c3a67c9c61c27d3dde..9538684c9b4e036994d38408912efb75d7a21bed 100644 (file)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1416,6 +1416,12 @@ 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 d7d900ebcf37fb61d57bd6772c3ca0e9305fef29..497a7249f2584cb1b27153d960be3f99065a9a43 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1468,6 +1468,9 @@ 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 15296f2c902cd358f923663fefacaf0dca5171b6..e03ff2a7a73fb067f047eb19e0109cf46262a651 100644 (file)
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -94,6 +94,7 @@ 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);