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    Subject[ 058/104] ALSA: usb: Add quirk for 192KHz recording on E-Mu devices
    Date
    3.8-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Calvin Owens <jcalvinowens@gmail.com>

    commit 1539d4f82ad534431cc67935e8e442ccf107d17d upstream.

    When recording at 176.2KHz or 192Khz, the device adds a 32-bit length
    header to the capture packets, which obviously needs to be ignored for
    recording to work properly.

    Userspace expected: L0 L1 L2 R0 R1 R2
    ...but actually got: R2 L0 L1 L2 R0 R1

    Also, the last byte of the length header being interpreted as L0 of
    the first sample caused spikes every 0.5ms, resulting in a loud 16KHz
    tone (about the highest 'B' on a piano) being present throughout
    captures.

    Tested at all sample rates on an E-Mu 0404USB, and tested for
    regressions on a generic USB headset.

    Signed-off-by: Calvin Owens <jcalvinowens@gmail.com>
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    sound/usb/card.h | 1 +
    sound/usb/pcm.c | 2 +-
    sound/usb/quirks.c | 1 +
    sound/usb/stream.c | 1 +
    4 files changed, 4 insertions(+), 1 deletion(-)

    --- a/sound/usb/card.h
    +++ b/sound/usb/card.h
    @@ -116,6 +116,7 @@ struct snd_usb_substream {
    unsigned int altset_idx; /* USB data format: index of alternate setting */
    unsigned int txfr_quirk:1; /* allow sub-frame alignment */
    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 running: 1; /* running status */

    --- a/sound/usb/pcm.c
    +++ b/sound/usb/pcm.c
    @@ -1161,7 +1161,7 @@ static void retire_capture_urb(struct sn
    stride = runtime->frame_bits >> 3;

    for (i = 0; i < urb->number_of_packets; i++) {
    - cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
    + cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset + subs->pkt_offset_adj;
    if (urb->iso_frame_desc[i].status && printk_ratelimit()) {
    snd_printdd(KERN_ERR "frame %d active: %d\n", i, urb->iso_frame_desc[i].status);
    // continue;
    --- a/sound/usb/quirks.c
    +++ b/sound/usb/quirks.c
    @@ -837,6 +837,7 @@ static void set_format_emu_quirk(struct
    break;
    }
    snd_emuusb_set_samplerate(subs->stream->chip, emu_samplerate_id);
    + subs->pkt_offset_adj = (emu_samplerate_id >= EMU_QUIRK_SR_176400HZ) ? 4 : 0;
    }

    void snd_usb_set_format_quirk(struct snd_usb_substream *subs,
    --- a/sound/usb/stream.c
    +++ b/sound/usb/stream.c
    @@ -94,6 +94,7 @@ static void snd_usb_init_substream(struc
    subs->dev = as->chip->dev;
    subs->txfr_quirk = as->chip->txfr_quirk;
    subs->speed = snd_usb_get_speed(subs->dev);
    + subs->pkt_offset_adj = 0;

    snd_usb_set_pcm_ops(as->pcm, stream);




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