On Sun, 2 Dec 2001, Mark Vojkovich wrote: > > On Sun, 2 Dec 2001, Billy Biggs wrote:
> > Why does it take so long to copy the data to the framebuffer? Can't > > we use DMA here? Does it really take that long to just copy 512k? > It's a little more than that because the driver is using > 4:2:2 internally. Copying the way it is doing you can't get > much more than 160 MB/sec and uses the CPU the whole time. > DMA won't make the transfer go any faster (it will probably > be slower unless you're using 2x+ AGP), but it won't eat the > CPU. The only drivers that do this are NVIDIA's binary > drivers and supposedly some experimental ATI drivers that > some people are working on. Maybe the i810 drivers do too, > not that it would help, since the bandwidth is probably the > same writing to video ram or the framebuffer. I thought the DMA'ified ATI-drivers were in the xfree86 CVS-tree by now? More or less on-topic links below. http://www.linuxvideo.org/lists/livid-gatos/2001-September/msg00007.html http://www.mail-archive.com/dri-devel@lists.sourceforge.net/msg01368.html http://www.xfree86.org/pipermail/xpert/2001-September/011481.html On another issue: Billy, check out the syncfb driver in the teletux project at sf. The CVS version is in active development. It gives way better performance than Xv on matrox cards, even though it is still mmio (AFAICT, which doesn't tell a lot). "Syncfb is a kernel module that synchronizes the output of video frames with the monitor frequency to avoid vertical artifacts (tearing) in the picture. This is done by creating a FIFO buffer inside the video ram of the graphics card and switching from one buffer to the next on vertical blanking interrupt. Syncfb also provides support for other video related hardware accelerations like scaling, hardware de-interlacing (usually only bi-linear interpolation of fields) and YUV->RGB conversion if available." Regards, Dag B _______________________________________________ Xpert mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xpert
