On Monday, March 6, 2006 12:28 pm, Thomas Hellström wrote: > The via driver has code that does this (via_dmablit.c) as a > device-specific IOCTL. > > It maintains a queue of blit operations and fire them off when the > previous one is completed. The user calls a sync IOCTL to verify that > the operation is finished.
Ok, thanks, I'll check it out. It looks like the CyberBlade device supports command queuing, maybe that would be a way to optimize the command submission stuff. > The via-specific code is quite limited, so it should be easy to port > it to other hardware but the card needs to have a descriptor-based PCI > DMA engine. Note that the throughput is quite low. With EXA you get > about 65-70 MB/s either direction. Limited by the PCI bus speed. Ok. I don't expect this system to be a speed demon either, but it does have SG support so hopefully I won't have to submit things in very small chunks. > If your card can do AGP->VRAM transfers in hardware the best option > for upload is probably to use that functionality. Software copies to > AGP can be pipelined with AGP->VRAM blits using two bounce-buffers in > AGP space. You split up the transfer and copy to one buffer while > you're blitting to VRAM from the other. Hm, I'll have to take a look at that. Based on the specs, it looks like the AGP transfer stuff is a separate command set. > For downloads from VRAM we will soon have an option to blit from VRAM > to AGP, and then take the pages out of AGP space and read from them > with full speed, but that's still under development. That sounds good, sounds like it should be fairly optimal. Thanks, Jesse ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid0944&bid$1720&dat1642 -- _______________________________________________ Dri-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/dri-devel
