Re: emu10k1 multichannel playback design (was Re: [PATCH] emu10k1: add interval timer support)

[Lee Revell <rlrevell@joe-job.com>]

On Sat, 2004-09-25 at 20:55, Lee Revell wrote:
> Looks good, until it Oops'es.  This is because currently the voice
> allocator only handles one or two voices at a time, it blows up as soon
> as I go to initialize the third voice.  I am working on this.

OK, I fixed the voice allocator to handle multichannel PCM.  Now it
looks like the prepare callback is being called over and over in a loop.

Here is the debug output from the prepare callback:

in snd_emu10k1_efx_playback_prepare - start_addr 0x1000 end_addr 0x11000
init voice - master 1 extra 0 start_addr 0x1000 end_addr 0x2000
init voice - master 1 extra 0 start_addr 0x2000 end_addr 0x3000
init voice - master 1 extra 0 start_addr 0x3000 end_addr 0x4000
init voice - master 1 extra 0 start_addr 0x4000 end_addr 0x5000
init voice - master 1 extra 0 start_addr 0x5000 end_addr 0x6000
init voice - master 1 extra 0 start_addr 0x6000 end_addr 0x7000
init voice - master 1 extra 0 start_addr 0x7000 end_addr 0x8000
init voice - master 1 extra 0 start_addr 0x8000 end_addr 0x9000
init voice - master 1 extra 0 start_addr 0x9000 end_addr 0xa000
init voice - master 1 extra 0 start_addr 0xa000 end_addr 0xb000
init voice - master 1 extra 0 start_addr 0xb000 end_addr 0xc000
init voice - master 1 extra 0 start_addr 0xc000 end_addr 0xd000
init voice - master 1 extra 0 start_addr 0xd000 end_addr 0xe000
init voice - master 1 extra 0 start_addr 0xe000 end_addr 0xf000
init voice - master 1 extra 0 start_addr 0xf000 end_addr 0x10000
init voice - master 1 extra 0 start_addr 0x10000 end_addr 0x11000
in snd_emu10k1_efx_playback_prepare - start_addr 0x1000 end_addr 0x11000
init voice - master 1 extra 0 start_addr 0x1000 end_addr 0x2000
init voice - master 1 extra 0 start_addr 0x2000 end_addr 0x3000

When I start jack, the above repeats endlessly.

Here is the prepare callback:

static int snd_emu10k1_efx_playback_prepare(snd_pcm_substream_t * substream)
{
        emu10k1_t *emu = snd_pcm_substream_chip(substream);
        snd_pcm_runtime_t *runtime = substream->runtime;
        emu10k1_pcm_t *epcm = runtime->private_data;
        unsigned int start_addr, end_addr;

        start_addr = epcm->start_addr;
        end_addr = epcm->start_addr + snd_pcm_lib_buffer_bytes(substream);
        printk("in snd_emu10k1_efx_playback_prepare - start_addr 0x%x end_addr 0x%x\n", start_addr,end_addr);

        /*
         * now we need to divide the buffer into 16 chunks and initialize
         * 16 voices to make the noninterleaved 16 channel stream
         */
        unsigned int channel_size;
        int i;
        channel_size = ( end_addr - start_addr ) / 16;
        for (i = 0; i < 16; i++) {
            snd_emu10k1_pcm_init_voice(emu, 1, 0, epcm->voices[i],
                                   start_addr, start_addr+channel_size);
            start_addr += channel_size;
        }
   
        return 0;
}

I am still missing parts of the driver, like the interrupt handler.  But
it seems like the prepare callback should not loop this way.  Am I doing
something wrong?

Lee



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