[alsa-devel] Input/output error while playing a file using aplay

[Pharaoh .]

wait..wait.....I need to use locking here...let me send you log after
doing locking appropriately .....

On 6/26/07, Pharaoh . <pharaoh137 at gmail.com> wrote:
> >It would really help if you'd show us the code of the version of the
> >driver that you're currently talking about.
>
> Hi Clemens...
>
> I had sent you the source file having pcm callbacks yesterday, now I
> have modified the pointer function as follows, I am just giving the
> pointer function here to avoid duplication, but please let me know in
> case you want to have look at the entire file.
>
>
> static snd_pcm_uframes_t snd_omap_alsa_pointer(snd_pcm_substream_t
> *substream)
> {
>
>         struct omap_eac *chip = snd_pcm_substream_chip(substream);
>         snd_pcm_uframes_t pos = 0;
>
>         FN_ENTER;
>         pos = audio_get_dma_pos(&chip->s[substream->pstr->stream]);
>         printk("Returning pos = %d\n", pos);
>         return pos;
>         FN_EXIT;
> }
>
> static snd_pcm_uframes_t audio_get_dma_pos(struct audio_stream *s)
> {
>         snd_pcm_substream_t *substream = s->stream;
>         snd_pcm_runtime_t *runtime = substream->runtime;
>         unsigned long flags;
>         dma_addr_t count;
>         unsigned long offset;
>         dma_addr_t src,dest;
>
>          if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
>                 dest = omap_get_dma_dst_pos(s->lch[s->dma_q_head]);
>                 offset = dest - runtime->dma_addr;
>                 printk("dest is %u and offset is %u\n",dest,offset);
>          } else {
>                 src = omap_get_dma_src_pos(s->lch[s->dma_q_head]);
>                 offset = src - runtime->dma_addr;
>                 printk("src is %u and offset is %u\n",dest,offset);
>          }
>
>         return bytes_to_frames(substream->runtime, offset);
> }
>
>
> And the log is as follows.
>
> For the first time.
>
>
> snd_omap_alsa_pointer start
> src is 3246792928 and offset is 3304194048
> Returning pos = 20742144
> Inside snd_pcm_update_hw_ptr_pos, pos is 20742144
> ALSA sound/core/pcm_lib.c:167: BUG: stream = 0, pos = 0x13c8000,
> buffer size = 0x4000, period size = 0x800
> returning pos 20742144
>
> I can see things are horribaly wrong here....
>
>
> On 6/26/07, Clemens Ladisch <cladisch at fastmail.net> wrote:
> > Pharaoh . wrote:
> > > After rewriting the pointer function
> >
> > It would really help if you'd show us the code of the version of the
> > driver that you're currently talking about.
> >
> > > I am not getting the input/output error but I am getting underruns.
> > > ...
> > > ALSA sound/core/pcm_lib.c:167: BUG: stream = 0, pos = 0x1150000, buffer
> > size = 0x4000, period size = 0x800
> >
> > Here, "pos" is the value returned by your pointer callback.  This value
> > should have been a frame number somewhere in the buffer, i.e., in the
> > range 0..0x3fff.  Apparently, the pointer callback doesn't correctly
> > calculate this value.
> >
> > Please remove most printk()s, and add some in the pointer callback to
> > show both the value that you get from the DMA controller, and the value
> > that this function returns.
> >
> >
> > Regards,
> > Clemens
> >
>