lkml.org 
[lkml]   [2002]   [Jan]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [linux-usb-devel] Re: highmem and usb [was "sr: unaligned transfer" in 2.5.2-pre1]
    On Wed, Jan 02 2002, David Brownell wrote:
    > > > requirement for drivers is that the transfer buffers can be passed to
    > > > pci_map_single() calls by the Host Controller Drivers (HCDs). The
    > > > device drivers, and URBs, don't expose such mappings, they only
    > > > require that they can be created/destroyed.
    > >
    > > .. which is the requirement that you want to change to use pci_map_page
    > > or pci_map_sg
    >
    > OK, I think I'm clear on this much then: in 2.5, to support block drivers
    > over USB (usb-storage only, for now) there needs to be an addition to
    > the buffer addressing model in usbcore, as exposed by URBs.
    >
    > - Current "transfer_buffer" + "transfer_buffer_length" mode needs to
    > stay, since most drivers aren't block drivers.

    Why? Surely USB block drivers are not the only ones that want to support
    highmem.

    > - Add some kind of "page + offset" addressing model.

    Yes

    > Discussion of details can be taken off LKML, it'd seem. Though I'm
    > curious when the scatterlist->address field will vanish, making these
    > changes a requirement. Is that a 2.5.2 thing?

    Maybe 2.5.3, dunno for sure.

    > Also, I noticed that include/asm-sparc/pci.h doesn't include the
    > standard pci_map_page() call ... what's up with that? That surely
    > causes portability problems.

    It probably isn't up to snuff yet.

    --
    Jens Axboe

    -
    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 13:15    [W:0.022 / U:0.156 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site