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    SubjectHow to detect ongoing activity on PCI/AGP?
    Date
    Hi,
    After upgrading my graphics, matrox g400 AGP to radeon rv280 AGP, I
    noticed severe horizontal distortions in outputted image (parts move
    randomly a pixel-or-two right or left).
    I tracked it down to my use of amd76x_pm module, which supposedly
    disconnects CPU's (this is 2xK7 SMP) from PCI bus. If I unload the
    module or simply make it less aggressive (== effective), horizontal
    distortions disappear.
    Needless to say, matrox g400 hadn't these.

    Similar distortions, although more visible and permanent, can be seen in
    this grab from a bt878 card. These are not something new, I always
    needed to remove amd76x_pm prior using the TV card.
    <http://varg.dyndns.org/psi/random/tvtime-output.jpg.html>
    Note that these distorted lines stay that way for a long time, sometimes
    over a second, so there's clearly something getting broken while
    transferring data via PCI.

    So I've been thinking along the lines if there was a way to detect
    active transfer on PCI and not do idling thing in amd76x_pm idle(). I
    took a look at various places in the kernel, but didn't find anything
    that matched.

    Closest thing I found was this piece from drivers/pci/pci.c:pci_disable_device
    - -
    pci_read_config_word(dev, PCI_COMMAND, &pci_command);
    if (pci_command & PCI_COMMAND_MASTER) {
    - -

    dev would likely to be northbridge, but would this work? Is there some
    other Right(tm) way to do this?

    Thanks,
    --
    Psi -- <http://www.iki.fi/pasi.savolainen>

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