On Sun, Feb 14, 2010 at 7:44 PM, Thomas Backlund <tmb@xxxxxxxxxxxx> wrote: > Larry Finger skrev 14.2.2010 18:36: >> >> On 02/14/2010 03:53 AM, Thomas Backlund wrote: >>> >>> Hi, >>> (please cc me on replies) >>> >>> We have a user that tried out b43, but got this in the logs: >>> >>> --- cut --- >>> 65858:Feb 9 22:05:16 elmo kernel: b43-phy2 ERROR: This device does not >>> support DMA on your system. Please use PIO instead. 65859:Feb 9 >>> 22:05:16 elmo kernel: b43-phy2 ERROR: CONFIG_B43_FORCE_PIO must >>> be set in your kernel configuration. >>> 65860:Feb 9 22:05:16 elmo kernel: b43-phy2 debug: Adding Interface type >>> 2 >>> 65861:Feb 9 22:05:16 elmo kernel: b43-phy2 ERROR: Fatal DMA error: >>> 0x00000400, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 >>> >>> 65862:Feb 9 22:05:16 elmo kernel: b43-phy2 ERROR: This device does not >>> support DMA on your system. Please use PIO instead. >>> 65863:Feb 9 22:05:16 elmo kernel: b43-phy2 ERROR: CONFIG_B43_FORCE_PIO >>> must be set in your kernel configuration. >>> --- cut --- >>> >>> >>> >>> But reading the Kconfig help, it states: >>> --- cut --- >>> config B43_FORCE_PIO >>> bool "Force usage of PIO instead of DMA" >>> depends on B43&& B43_DEBUG >>> ---help--- >>> This will disable DMA and always enable PIO instead. >>> >>> Say N! >>> This is only for debugging the PIO engine code. You do >>> _NOT_ want to enable this. >>> --- cut --- >>> >>> >>> So, >>> wich one is it ? >>> >>> Do I belive the dmesg output, or the Kconfig ? >>> >>> Note, >>> the b43 works for the user if he enable the CONFIG_B43_FORCE_PIO. >>> >>> But I'm thinking of this problem from a distro point of view. >>> Will it break for others if I enable it ? >> >>> From a distro point of view, you would not want to set FORCE_PIO as the >> >> performance penalty would be very large. >> > > As I suspected. > Thanks for confirming it. > >> You do not give the specific details on the problem system; however, it is >> probably a BCM4312 802.11 b/g device with PCI ID 14e4:4315 being used with >> an >> Atom processor in a netbook. We have no fix. >> > > Sorry about the missing info... > I asked a few times from the user, and got no reponse until today a few > hours after your response... > > It is indeed a BCM4312 802.11 b/g device with PCI ID 14e4:4315 on a Dell > laptop with a Intel ICH9M series chipset and a Intel Core(TM)2 Duo CPU T7250 > @ 2.00GHz. Weird... that's not an Intel Atom, but a Core 2 Duo, standard-voltage. Mind posting any more details on this system? > >> In the 2.6.34 code, b43 will be changed to allow the selection of PIO mode >> at >> run time rather than compile time. For a distro, this method is clearly >> superior. Those users that need PIO can select it without forcing the >> performance penalty on everyone. The patch was too late for the 2.6.33 >> merge, >> and too intrusive to be applied to 2.6.33-rcX. It has been present in the >> wireless-testing code base for 2 months with no trouble reported, thus it >> should >> be safe for inclusion in your kernels. The relevant patch is attached. >> > > Nice solution. > > What about making it autodetected ? > Or is it only a "last resort" with the hopes of getting the issue fixed? > > Anyway, thanks for the patch. > > -- > Thomas > -- > To unsubscribe from this list: send the line "unsubscribe linux-wireless" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-) -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
