[alsa-devel] ASUS Phoebus (CMI8888) HDA Support
geoff at spacevs.com
Wed Dec 4 23:20:59 CET 2013
Interestingly I added some code to dump out the DMA addresses used and
checked it with and without IOMMU:
DMA: AREA = ffff8800dd44b000, ADDR = dd44b000
DMA: AREA = ffff8803ecf15000, ADDR = 68000
Here are the registers while the device is working (with IOMMU):
CORBLBASE gets set to dd44b000, and RIRBLBASE gets set to dd44b800 when
it is without IOMMU as one would expect.
But... it is not 128bit aligned as per the HD Audio Spec.
Windows uses a DMA address of 0xdd4d0000, which is 128bit aligned. I
will do some more hacking and see if I can figure out how to give it an
aligned DMA buffer.
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