Hi.
I've now commited the via PCI DMA bitblt code to DRM CVS
The first client will probably be Xv image transfer.
Some caveats:
*Needs porting to FreeBSD.
*Transfer rate is not very fast. About 50MB/s including building and
destroying mappings. The big gain is transferring from frame-buffer to
system memory where otherwise the transfer rates are much slower, and
off-loading the CPU during all transfers. This reduces X server CPU
usage on, for example, K8M800 chips from about 25% to 2% watching DVD
using Xv.
*VIA docs are rumored to require the (src_addr%4 == dest_addr%4) for all
lines, and this is what is implemented as a sanity check. However,
apparently there is a bug in the chip that also requires (system_addr&15
== 0) for all lines. VIA has been contacted about this, but have failed
to provide any answers. If these alignments cannot be met, a user-space
bounce buffer needs to be used, and this will be implemented for Xv.
/Thomas
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