Re: [Madwifi-devel] Long distance problems - Atheros 5211

[Jim T. <ji...@te...>]

Marcin Pilch said:
>
>>
>> There was some discussion going on earlier about changing the slot time.
>> You can find the default settings in the ah.h file if I remember
>> correctly. The defaults were 9us and 20us. Have you tried increasing
>> these? In the changelog for the ah.h file it mentions the following
>> implement ah_setSlotTime for 5211 parts.
>> I need to tackle this after the first of the year also and would be
>> interested in knowing what you find out.
>> Jim
>>
>
> I tried changing these values (from 21 to 100+), and I tried calling the
> ah_setSlotTime from several places inside the driver.
>
> +if (ah->ah_setSlotTime(ah, HAL_SLOT_TIME_20)==AH_TRUE)
> +	printk("success - setting slot time\n"); else
> +	printk("failure - setting slot time\n");
>
> According to the discussion about changing the slot time you mentioned
> (available at
> http://sourceforge.net/mailarchive/forum.php?thread_id=3483397&forum_id=33958
> ) we need to change the slot time _and_ the ack time. There is also a
> note, that it works only on Atheros 5212, but ah_setSlotTime always
> returned AH_TRUE in my case.
>
> Where should I put ah_setSlotTime call, and what about setting the ack
> time?
I am sure where you would set the ah_setSlotTime call but I was digging
around at the Star-OS site as they are also working in the Atheros 5212
and 5211 and they had posted the following concerning ack timing


When adjusting the ACK values, use these guidelines:

Atheros ar5212 cards - default ACK values:
802.11b mode: 450.
802.11a mode: 180.
802.11g mode: 180.

Atheros ar5211 chards - default ACK values:
802.11a mode: 180
802.11b mode: 230

The values above represent the hardware defaults for the cards we have.
When you wish to adjust for a longer link, increase the numbers beyond the
values shown. Setting the value back to 0 will use the card's default.

For example, if you wish to extend a 5.8 link, try using a value of 400 or
more as a starting point.

All values are 1/4 of a microsecond (usec). 100usec equals an ACK value of
400.

Has anybody else on the list made any headway on this yet?

Jim