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| author | Maciej S. Szmigiero <mail@maciej.szmigiero.name> | 2018-02-14 02:07:58 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2018-02-14 09:46:55 +0300 |
| commit | 04f8773a3e980f60953e7aeb36ec6c2631e11f10 (patch) | |
| tree | d6acfcbfd79924f50f46886683ca6c5f391d0b4f /sound/pci/emu10k1/emupcm.c | |
| parent | 055e0ae10f509482ca5b140e8e5f4a77e31efdd5 (diff) | |
| download | linux-04f8773a3e980f60953e7aeb36ec6c2631e11f10.tar.xz | |
ALSA: emu10k1: add a IOMMU workaround
The Audigy 2 CA0102 chip (but most likely others from the emu10k1 family,
too) has a problem that from time to time it likes to do few DMA reads a
bit beyond its normal allocation and gets very confused if these reads get
blocked by a IOMMU.
For the first (reserved) page this happens multiple times at every
playback, for various synth pages it happens randomly, rarely for PCM
playback buffers and the page table memory itself.
All these reads seem to follow a similar pattern, observed read offsets
beyond the allocation end were 0x00, 0x40, 0x80 and 0xc0 (PCI cache line
multiples), so it looks like the device tries to accesses up to 256 extra
bytes.
As a workaround let's widen these DMA allocations by an extra page if we
detect that the device is behind a non-passthrough IOMMU (the DMA memory
should be relatively plenty on IOMMU systems).
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/pci/emu10k1/emupcm.c')
| -rw-r--r-- | sound/pci/emu10k1/emupcm.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/sound/pci/emu10k1/emupcm.c b/sound/pci/emu10k1/emupcm.c index 2683b9717215..cefe613ef7b7 100644 --- a/sound/pci/emu10k1/emupcm.c +++ b/sound/pci/emu10k1/emupcm.c @@ -411,12 +411,20 @@ static int snd_emu10k1_playback_hw_params(struct snd_pcm_substream *substream, struct snd_emu10k1 *emu = snd_pcm_substream_chip(substream); struct snd_pcm_runtime *runtime = substream->runtime; struct snd_emu10k1_pcm *epcm = runtime->private_data; + size_t alloc_size; int err; if ((err = snd_emu10k1_pcm_channel_alloc(epcm, params_channels(hw_params))) < 0) return err; - if ((err = snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params))) < 0) + + alloc_size = params_buffer_bytes(hw_params); + if (emu->iommu_workaround) + alloc_size += EMUPAGESIZE; + err = snd_pcm_lib_malloc_pages(substream, alloc_size); + if (err < 0) return err; + if (emu->iommu_workaround && runtime->dma_bytes >= EMUPAGESIZE) + runtime->dma_bytes -= EMUPAGESIZE; if (err > 0) { /* change */ int mapped; if (epcm->memblk != NULL) |