On Wed, Jan 16, 2013 at 06:32:09PM +0100, Soeren Moch wrote: > On 16.01.2013 09:55, Soeren Moch wrote: > >On 16.01.2013 04:24, Soeren Moch wrote: > >>I did not bisect it, but Marek mentioned earlier that commit > >>e9da6e9905e639b0f842a244bc770b48ad0523e9 in Linux v3.6-rc1 introduced > >>new code for dma allocations. This is probably the root cause for the > >>new (mis-)behavior (due to my tests 3.6.0 is not working anymore). > > > >I don't want to say that Mareks patch is wrong, probably it triggers a > >bug somewhere else! (in em28xx?) > > The em28xx sticks are using isochronous usb transfers. Is there a > special handling for that? I'm looking at that now. It looks like the em28xx wants (as a maximum) 655040 bytes (em28xx-core.c:1088). There are 5 transfer buffers, with 64 max packets and 2047 max packet size (runtime reported max & 0x7ff). If it actually needs all of that, then the answer may be to just increase coherent_pool= when using that driver. I'll keep digging. thx, Jason. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>