Commit Graph

2 Commits

Author SHA1 Message Date
David Brownell fbf54dd320 USB: usb/dma doc updates
This patch updates some of the documentation about DMA buffer management
for USB, and ways to avoid extra copying.  Our understanding of the issues
has improved over time.

 - Most drivers should *avoid* the dma-coherent allocators.  There are
   a few exceptions (like the HID driver).

 - Some methods are currently commented out; it seems folk writing
   USB drivers aren't doing performance tuning at that level yet.

 - Just avoid highmem; there's no good way to pass an "I can do highmem
   DMA" capability through a driver stack.  This is easy, everything
   already avoids highmem.  But it'd be nice if x86_32 systems with much
   physical memory could use it directly with network adapters and mass
   storage devices.  (Patch, anyone?)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-07-12 16:34:42 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00