At Fri, 02 Jun 2006 18:51:45 +0200,
Lars Bergmann wrote:
>
> I see two types of failure:
> 1) PCI audio device drivers exit with snd_pcm_mmap_data_nopage (see below)
This is a known problem. A workaround patch for ARM is below, but it
still doesn't work for some devices with SG buffer.
A better but more intrusive fix is pending on my tree, which will be
hopefully merged sometime later.
> 2) USB audio driver plays for some seconds (reporting underruns) and
> will then fail:
>
> # /usr/local/bin/aplay /home/lars/tori-test-48k.wav
> Playing WAVE '/home/lars/tori-test-48k.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
> underrun!!! (at least 4.662 ms long)
> underrun!!! (at least 0.134 ms long)
> underrun!!! (at least 25.856 ms long)
> underrun!!! (at least 0.138 ms long)
> underrun!!! (at least 5.296 ms long)
> ...
> aplay: pcm_write:1222: write error: Input/output error
> timeout: still 12 active urbs..
> # usb 1-2: USB disconnect, address 2
>
> Playback via USB audio will also produce stack traces from either khubd
> or pdflush (see below).
>
> PCI and USB problems might be completely unrelated: Looking at the USB
> audio driver, I think they did not use ALSA API for memory allocation
> and I/O mapping - instead they create URBs allocated by the USB core.
The usb-audio driver does memory allocation and mmaping indeed.
Takashi
diff -r c11fa10a4838 core/pcm_native.c
--- a/core/pcm_native.c Tue Jun 06 15:44:34 2006 +0200
+++ b/core/pcm_native.c Tue Jun 06 16:24:57 2006 +0200
@@ -3124,6 +3124,10 @@ static int snd_pcm_mmap_control(struct s
}
#endif /* coherent mmap */
+#if defined(CONFIG_ARM)
+#define HAVE_DMA_MMAP_COHERENT
+#endif
+
/*
* nopage callback for mmapping a RAM page
*/
@@ -3167,6 +3171,14 @@ static struct vm_operations_struct snd_p
.nopage = snd_pcm_mmap_data_nopage,
};
+#ifdef HAVE_DMA_MMAP_COHERENT
+static struct vm_operations_struct snd_pcm_vm_ops_data_one_map =
+{
+ .open = snd_pcm_mmap_data_open,
+ .close = snd_pcm_mmap_data_close,
+};
+#endif
+
/*
* mmap the DMA buffer on RAM
*/
@@ -3176,6 +3188,16 @@ static int snd_pcm_default_mmap(struct s
area->vm_ops = &snd_pcm_vm_ops_data;
area->vm_private_data = substream;
area->vm_flags |= VM_RESERVED;
+#ifdef HAVE_DMA_MMAP_COHERENT
+ if (substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV) {
+ area->vm_ops = &snd_pcm_vm_ops_data_one_map;
+ if (dma_mmap_coherent(substream->dma_buffer.dev.dev, area,
+ substream->runtime->dma_area,
+ substream->runtime->dma_addr,
+ area->vm_end - area->vm_start))
+ return -EAGAIN;
+ }
+#endif
atomic_inc(&substream->mmap_count);
return 0;
}
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