On Fri, Nov 13, 2009 at 5:05 PM, Larry Finger <[email protected]> wrote: > On 11/13/2009 05:16 AM, Michael Buesch wrote: >> Ok, so my guess is that the DMA allocator simply returned high memory >> that was unusable to the device. My new code explicitly checks for that (and >> a >> few other things) and retries with GFP_DMA in case the address has illegal >> bits set. >> That's the same thing we do for the frame buffers, so I don't see anything >> wrong with it. >> >> Yeah, the new code is big and scary, but I think it makes a whole lot more >> sense than >> what we have now. Especially if I add some comments and do more cleanups. > > I agree that the new code makes a lot of sense. I'm also beginning to believe > that the problem lies outside b43, and that it is merely triggered by some > interaction with ACPI and/or the BIOS. From what I found in looking back > through > the DMA error reports, most (if not all) people with the problem have netbook > computers with Intel ATOM processors. > > I am considering posting on LKML and the ACPI mailing lists to see if we can > get > any ideas from those experts. Please comment on the draft text below: > > ============================ > > A number of users are experiencing DMA descriptor or data errors using 64-bit > DMA with the Broadcom BCM4312 wireless device. After careful review and a > rewrite of the DMA code in the driver, we have not been able to fix the > problem, > but we have determined the following: > > (1) The problem is much more likely to occur on netbook systems. Several of > the > developers have this card in regular notebook systems. None of us have the > problem, thus it may occur only on netbooks, but several brand/model > combinations are affected including Dell Inspiron 910 and Acer Aspire One > A150.
Linus has also reported this issue on a Core 2 ULV. I suspect that the key part is deep-sleep support in the CPU. Also, PhoenixBIOS seems to play part in the problem. > > (2) If CONFIG_ACPI_PROCESSOR is not set on affected systems, the error rate is > much lower. > > (3) When a DMA descriptor error occurs, a dump of the descriptors does not > reveal any obvious problems. > > I do not know enough about either the ACPI or DMA code to begin debugging in > either of those regions. Any suggestions on debugging strategies, or links to > similar problems would be appreciated. > > ============================ > > Larry > > -- Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-) _______________________________________________ Bcm43xx-dev mailing list [email protected] https://lists.berlios.de/mailman/listinfo/bcm43xx-dev
