lkml.org 
[lkml]   [2002]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH] IDE 58
    Date
    >
    >Please push it higher level than that. Load the taskfile as a set in
    >each method. Remember its 1 potentially paired instruction to do an MMIO
    >write, its a whole mess of synchronziation and stalls to do a function
    >pointer.

    I though about that, but what about corner cases where only a single
    register can be accessed ? (typically alt status). Provide specific
    routines ? Also, how does the extended addressing works ? by writing
    several times to the cyl registers ? That would have to be dealt with
    as well in each host driver then.

    >> address at all (that is kill the array of port addresses) but
    >> just pass the taskfile_in/out functions the register number
    >> (cyl_hi, cyl_lo, select, ....) as a nice symbolic constant,
    >> and let the channel specific implementation figure it out.
    >
    >Pass dev->taskfile_load() a struct at least for the common paths. Make the
    >PIO block transfers also single callbacks for each block not word.

    Right. We could go the darwin (apple) way and have taskfile_load/store
    functions doing the entire registers controlled by a bitmask of which
    registers has to be touched. it has a cost (testing each bit and
    conditionally branching, which can suck hard) but probably less than
    an indirect function call which isn't predictable.

    Ben.

    -
    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 13:25    [W:0.022 / U:5.316 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site