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Thread: Using Six Monitors With AMD's Open-Source Linux Driver

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  1. #11
    Join Date
    Dec 2007


    Quote Originally Posted by Brane215 View Post
    Could you elaborate on that ? Up untl now I thought the bottleneck is in framing circuits, since each frame is just a packet on Displayport while it has to be framed on other outputs ( X pixels in a row in Y rows with certain bit organisation within pixel and timings so it reaches the "phosphor" at exactly right moment).

    Your post implies that actually good PLL is expensive part wrt to silicon area and that ATI has been skimping on PLLs, not framing circuits.

    If so, it would be nice to know how could one drive M identical monitors at identical framerate and resolution with one PLL.

    Had I known how to do it before, it would spare me from much of the headscratching, endless googling, many failed attempts with passive adapters ( basically just a piece of wire and two connectors), suffering with DP-VGA adapter and using the latest addition XFX DP-DVI active adapter.

    Active adapters are not that cheap and adapters for dual-link DVI are outrageously expensive...
    The DP requirement was a major point of all of the initial eyefinity reviews and I've mentioned it on my blog several times. It also says on the product packaging that more than two displays requires additional displays be DP. Having fewer PLLs saves power and die area and most people don't use more than two monitors at the moment. DP runs at a fixed clock regardless of the mode so you can run multiple streams off the same PLL. Non-DP requires a dedicated clock per stream as the clock varies based on the mode. You can use the same PLL if multiple modes share the same clock. Things like PLL sharing are complex to validate and confusing to users since users may run two or more monitors at the same mode, and then try and change the mode on one of the monitors only to have the driver report that it's not possible due to PLL limitations. AMD only officially supports two non-DP monitors with eyefinity for that reason.
    Last edited by agd5f; 05-20-2013 at 10:41 AM.

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