Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q9

From: Alan Cox (alan_at_lxorguk.ukuu.org.uk)
Date: 09/04/04

  • Next message: Alan Cox: "Re: [Umbrella-devel] Re: Getting full path from dentry in LSM hooks" 
    To: Lee Revell <rlrevell@joe-job.com>
Date:	Sat, 04 Sep 2004 17:52:14 +0100

    On Sad, 2004-09-04 at 01:04, Lee Revell wrote:
    > This is looking more and more like a video driver problem:

    Not really. The delay is too small and X is smarter than this. (except a
    VIA case that only recently got squished).

    > The video cards have a command FIFO that is written to via the PCI bus.
    > They also have a status register, read via the PCI bus, which says
    > whether the command FIFO is full or not. The hack is to not check
    > whether the command FIFO is full before attempting to write to it, thus
    > saving a PCI bus read.

    On problem cards X defaults to polling the status FIFO. You can tell it
    to be rude but you have to actively do so. Newer PCI 2.x specs also have
    a thing or two to say on the subject

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