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Re: iBook and playing DVDs



>What about a mixed approach to avoid unnecessary bus traffic: try to read
>the ring head pointer from memory, and if after a timeout the free ring space
>still doesn't seem to be large enough, read it directly from the register.
>This could hurt performance badly if the memory copy is often outdated
though.

Well, let's first make it stable...
>
>> >If apps would at least avoid reading stuff written
>> >by the video card, write-through cached would be OK.
>> >Apps that read AGP memory are uncommon enough that
>> >fixing all of them would be feasible.
>> 
>> I think we can use full caching (copyback) without too much
>> problems. In the r128 case, we'll have to flush from the X server
>> as it's directly writing to the ring (and maybe from the mesa driver
>> as well). On radeon, it's all done via indirect buffers and those
>> get passed to the kernel driver before beeing inserted in the ring.
>
>Where is r128 different than radeon in this respect?

The last time I looked at r128, it wrote to the ring directly iirc,
while radeon on wrote to indirect buffers, the kernel putting them
in the ring. This may have changed though.

Ben.




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