snd_hda: Enable bus_dmamap_sync operations, both new and uncommented
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Authored by jhibbits on Jul 30 2018, 8:12 PM.

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mav
mmel

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rS337043: snd_hda: Synchronize DMA buffers for the control path

Summary

Make sure both sides of the memory accesses in snd_hda (device and CPU)
can see coherent memory. This is needed on weakly ordered architectures
including PowerPC and ARM. Patch originally by mmel, with small changes.

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rS FreeBSD src repository - subversion

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Buildable 18443
Build 18150: arc lint + arc unit

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jhibbits created this revision.Jul 30 2018, 8:12 PM

Herald added a subscriber: imp. · View Herald TranscriptJul 30 2018, 8:12 PM

Harbormaster completed remote builds in B18443: Diff 46042.Jul 30 2018, 8:12 PM

The commit message is a bit misleading. This patch ensures DMA coherency only for control structures but audio data buffers are not covered by required bus_dmamap_sync() operations. (We simply don't have right sync operation for syncing in progress DMA buffers - something like make buffer range snapshot before CPU read and make buffer range snapshot after CPU write).
Can you, please, elaborate this fact in commit message.

Otherwise, LGTM.

This revision is now accepted and ready to land.Aug 1 2018, 8:40 AM

Closed by commit rS337043: snd_hda: Synchronize DMA buffers for the control path (authored by jhibbits). · Explain WhyAug 1 2018, 2:50 PM

This revision was automatically updated to reflect the committed changes.