lkml.org 
[lkml]   [2004]   [Jan]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC] Relaxed PIO read vs. DMA write ordering
    On Wed, Jan 07, 2004 at 03:27:54PM -0800, Greg KH wrote:
    > On Wed, Jan 07, 2004 at 03:07:12PM -0800, Jesse Barnes wrote:
    > >
    > > 1) add pcix_enable_relaxed() and read_relaxed() (read() would always be
    > > ordered)
    >
    > This probably preserves the current situation best, enabling driver
    > writers to be explicit in knowing what is happening.
    >
    > thanks,
    >
    > greg k-h

    I like this best too. That way, a driver can enable a relaxed read
    in the performance path and not have to audit the other reads.

    So in a generic PCI driver, you'd call pcix_enable_relaxed() and
    then use read() for initialization, error recovery, etc., and
    use read_relaxed() in the main execution path where it is determined
    to be safe.

    The default would be the standard behavior that we have.

    One question I have is what the need for pcix_enable_relaxed() is.
    Are we thinking that this sets some bit in one or more registers?
    What happens if you use read_relaxed() and you didn't call
    pcix_enable_relaxed() previously?

    jeremy
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:59    [W:0.023 / U:153.572 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site