Larry Finger skrev 14.2.2010 18:36:
quoted text > 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.
quoted text > 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.
quoted text > 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 netdev" in
the body of a message to
majordomo@vger.kernel.org
More majordomo info at
http://vger.kernel.org/majordomo-info.html
