Messages in this thread | | | Date | Mon, 18 Dec 2006 10:54:16 -0500 | From | Gene Heskett <> | Subject | Re: ieee1394 in 2.6.20-rc1 (was Re: Linux 2.6.20-rc1) |
| |
On Monday 18 December 2006 10:45, Stefan Richter wrote: >Gene Heskett wrote: >> On Sunday 17 December 2006 20:05, Stefan Richter wrote: >>>What's missing in our implementation is that the use count of ohci1394 >>>goes up too once a "high-level driver" uses resources of a host driven >>>by ohci1394. >> >> This needs some tlc then I assume? > >Yes. It's now logged at http://bugzilla.kernel.org/show_bug.cgi?id=7701 >and will probably stay there until I do something about it myself.
Thanks, that pretty well describes what happened here.
>>>The FireWire stack has three layers: Low level (ohci1394 and pcilynx; >>>control the host bus adapter), >> >> The hardware > >Yes, or more precisely the built-in hardware, not hardware at the other >end of the wire.
That was assumed when I wrote it :)
>>>mid level (the ieee1394 core) >> >> which I assume (fuggly word) steers the high level stuff to the right >> entry points in the hardware handler? > >Yes. It implements common management functionality and makes actions >like "write into a register of a remote node" or "receive a stream into >a buffer" independent of the actual host adapter --- or at least that >was the intent when Linux' FireWire stack was designed. Years ago there >was actually another driver for a non-OHCI host adapter chip from >Adaptec; and there is a mostly functional but unmaintained out-of-tree >driver for a non-OHCI/ non-PCI adapter from Texas Instruments (TI > GP2Lynx). > >IOW the ieee1394 core provides a platform to stick application-level >drivers (protocol drivers) like for DV, IPv4 networking, SBP-2 storage >on top of it without having to care of how particular host adapter chips >are programmed. raw1394 basically extends ieee1394 to stick userspace >drivers on it. > >But as mentioned, this layering is partly violated in the actual >implementation. Also, the ieee1394 core is itself needlessly dependent >on a PCI kernel API, making it harder for embedded developers to add >their own low-level drivers than it ought to be. (So I was told; I >actually rarely hear from embedded development projects.)
Typical :-) Don't let me distract you from more important work :)
-- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Yahoo.com and AOL/TW attorneys please note, additions to the above message by Gene Heskett are: Copyright 2006 by Maurice Eugene Heskett, all rights reserved. - 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/
| |