DM8168 audio with mcasp

I'm trying to use an I2S audio source from an ADV7604 with the mcasp 1 interface on a DM8168 Z3 board.  We've developed our own board which has the ADV7604 on it.  The ADV7604 is working with video, I can see I2S audio signals being generated by the ADV7604, I've added driver code to the linux kernel to handle the audio information, but I keep getting the message

arecord: pcm_read:1617: read error: Input/output error

when I try to do a capture with arecord.  I also get a dmesg of

capture write error (DMA or IRQ trouble?)

The arecord command I'm using is

arecord -Dhw:0,1 -t wav -f S32_LE -r 48000 -c 2 -d 5 tmp.wav

The I2S being sent by the digital HDMI source is 24 bit so I changed the driver to add support for 24 bit and tried

arecord -Dhw:0,1 -t wav -f S24_LE -r 48000 -c 2 -d 5 tmp.wav

but I get the same result.

The system is reporting the presence of the audio device correctly:

asoc: HDMI-DAI-CODEC <-> hdmi-dai mapping ok
asoc: adv7604-hifi <-> davinci-mcasp.1 mapping ok
ALSA device list:
  #0: TI81XX EVM

When I do "arecord -l" I get:

**** List of CAPTURE Hardware Devices ****
card 0: EVM [TI81XX EVM], device 1: ADV7604 adv7604-hifi-1 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0

The changes I made to the linux kernel are:

board-ti8168evm.c:

added:

static struct platform_device ti8168_adv7604_snd_driver = {
    .name    = "adv7604-sound",
    .id    = -1,
};

changed:

static u8 ti8168_mcasp1_serializer_direction[] = {
    RX_MODE,    RX_MODE,    INACTIVE_MODE,    INACTIVE_MODE,
    INACTIVE_MODE,    INACTIVE_MODE,    INACTIVE_MODE,    INACTIVE_MODE,
    INACTIVE_MODE,    INACTIVE_MODE,    INACTIVE_MODE,    INACTIVE_MODE,
    INACTIVE_MODE,    INACTIVE_MODE,    INACTIVE_MODE,    INACTIVE_MODE,
};


static struct snd_platform_data ti8168_evm_mcasp1_data = {
    .tx_dma_offset    = 0x46400000,
    .rx_dma_offset    = 0x46400000,
    .op_mode    = DAVINCI_MCASP_IIS_MODE,
    .num_serializer = ARRAY_SIZE(ti8168_mcasp1_serializer_direction),
    .tdm_slots    = 2,
    .serial_dir    = ti8168_mcasp1_serializer_direction,
    .asp_chan_q    = EVENTQ_1,
    .version    = MCASP_VERSION_2,
    .txnumevt    = 0,
    .rxnumevt    = 1,
};

in ti8168_evm_init:

        platform_device_register( &ti8168_adv7604_snd_driver );

I didn't make any changes in devices.c since it looked right for mcasp 1.

I added an adv7604.c sound driver file to sound/soc/codecs which has the "adv7604-sound" sound driver and the "adv7604-hifi"

I also added:

#if (defined(CONFIG_VIDEO_ADV7604) || defined(CONFIG_VIDEO_ADV7604_MODULE))
        {
                .name = "ADV7604_SOC_LINK",
                .stream_name = "ADV7604",
                .cpu_dai_name= "davinci-mcasp.1",
                .codec_dai_name = "adv7604-hifi",
                .codec_name = "adv7604-sound",
                .platform_name = "davinci-pcm-audio",
                .init = evm_adv7604_init,
                .ops = &evm_ext_master_ops,
        },
#endif

to the ti81xx_evm_init array in sound/soc/davinci/davinci-evm.c

It looks like everything is recognized and connected, but I keep getting the capture write error (DMA or IRQ trouble?) message.  I can see data being sent on the mcasp signals so I would expect to end up with a wav file filled with at least noise, but I didn't expect to keep getting this timeout.  I believe the message is being generated by the routine wait_for_avail in sound/core/pcm_lib.c.  It looks like it's waiting for data to become available, but none appears.

The kernel is linux 2.6.37 with PSP 04.04.00.01.

Anybody have any suggestions?

Carl