Re: RaLink RT2500 802.11g Cardbus/mini-PCI

["Thomas Bächler" <thomas@archlinux.org>]

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Johannes Berg schrieb:
>>> I compiled half a dozen kernels and now figured it out. This is the 
>>> patch that causes rt2500pci to be slow. If I revert it, it is fast again:
>>> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=d43c7b37ad787173d08683f05eadeea0398fefdf
> 
>> That's odd. But that patch looks a bit fishy now that I look at it, care
>> to try below change (manually, this isn't a patch)?
>>
>> johannes
>>
>>         bool use_protection = (erp_value & WLAN_ERP_USE_PROTECTION) != 0;
>> -       bool use_short_preamble = (erp_value & WLAN_ERP_BARKER_PREAMBLE) == 0;
>> +       bool use_short_preamble = (erp_value & WLAN_ERP_BARKER_PREAMBLE) != 0;
>>         DECLARE_MAC_BUF(mac);
> 
> No, wait, I'm confused, the original patch is correct. As far as I can
> tell, the code there is correct. The bug in that code was actually
> introduced by me based on the wrong thinking I just did again.

I figured as much from the original commit message. So rt2500pci works 
properly when the use_short_preamble has the wrong value, and breaks 
when it has the right one.
By the way, 2.6.25-rc8 was the first time that rt2500pci was ever fast 
enough to be usable at all for me, so the bug you introduced seemed to 
be the fix for my speed problems (which is odd). My guess is that 
rt2500pci treats use_short_preamble wrong.


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