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 de43267b9c8af77dca423d8a1bc6079323806ac9..5351d7183b1bdc74d5253fe5728d3a66ce6647a1 100644 (file)
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -137,6 +137,7 @@ 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 a69d9e75f66fe4c8a75e85ca1998950dbb3f7fae..eb3cececda79443646689228877b8d57c31305ab 100644 (file)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1420,6 +1420,12 @@ 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 fca72730a802ec617f267e858390babe37c56053..ef1c1cf040b45ef2c495bb77962f358c3518632e 100644 (file)
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1495,6 +1495,9 @@ void snd_usb_set_format_quirk(struct snd_usb_substream *subs,
        case USB_ID(0x2b73, 0x000a): /* Pioneer DJ DJM-900NXS2 */
                pioneer_djm_set_format_quirk(subs);
                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);