ALSA: asihpi - Improve non-busmaster adapter operation
Eliot Blennerhassett [Fri, 25 Mar 2011 02:25:47 +0000 (15:25 +1300)]
Make playback silence callback a no-op, card automatically outputs
silence when written data runs out.
Increasing update interval and thus minimum period avoids xrun on startup
or because of timer jitter.

Signed-off-by: Eliot Blennerhassett <eblennerhassett@audioscience.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/asihpi/asihpi.c

index 22606e3..c90d77a 100644 (file)
@@ -1012,6 +1012,7 @@ static int snd_card_asihpi_playback_open(struct snd_pcm_substream *substream)
 
        snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
                card->update_interval_frames);
+
        snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
                card->update_interval_frames * 2, UINT_MAX);
 
@@ -1054,7 +1055,7 @@ static int snd_card_asihpi_playback_copy(struct snd_pcm_substream *substream,
        hpi_handle_error(hpi_outstream_write_buf(dpcm->h_stream,
                                runtime->dma_area, len, &dpcm->format));
 
-       dpcm->pcm_buf_host_rw_ofs = dpcm->pcm_buf_host_rw_ofs + len;
+       dpcm->pcm_buf_host_rw_ofs += len;
 
        return 0;
 }
@@ -1064,16 +1065,11 @@ static int snd_card_asihpi_playback_silence(struct snd_pcm_substream *
                                            snd_pcm_uframes_t pos,
                                            snd_pcm_uframes_t count)
 {
-       unsigned int len;
-       struct snd_pcm_runtime *runtime = substream->runtime;
-       struct snd_card_asihpi_pcm *dpcm = runtime->private_data;
-
-       len = frames_to_bytes(runtime, count);
-       VPRINTK1(KERN_INFO "playback silence  %u bytes\n", len);
-
-       memset(runtime->dma_area, 0, len);
-       hpi_handle_error(hpi_outstream_write_buf(dpcm->h_stream,
-                               runtime->dma_area, len, &dpcm->format));
+       /* Usually writes silence to DMA buffer, which should be overwritten
+       by real audio later.  Our fifos cannot be overwritten, and are not
+       free-running DMAs. Silence is output on fifo underflow.
+       This callback is still required to allow the copy callback to be used.
+       */
        return 0;
 }
 
@@ -2885,6 +2881,9 @@ static int __devinit snd_asihpi_probe(struct pci_dev *pci_dev,
        if (err)
                asihpi->update_interval_frames = 512;
 
+       if (!asihpi->support_mmap)
+               asihpi->update_interval_frames *= 2;
+
        hpi_handle_error(hpi_instream_open(asihpi->adapter_index,
                             0, &h_stream));