Re: rt2800, minstrel_ht & mac80211

[Johannes Berg <johannes@sipsolutions.net>]

On Fri, 2010-06-04 at 12:22 +0200, Helmut Schaa wrote:

> This meant that minstrel most of the time selected MCS15 as tx rate which
> resulted in a huge number of retries and thus a very slow throughput.
> 
> status.c:
> 
> 178                 /* the HW cannot have attempted that rate */
> 179                 if (i >= hw->max_rates) {
> 180                         info->status.rates[i].idx = -1;
> 181                         info->status.rates[i].count = 0;
> 
> Johannes, is there a valid reason for this check in status.c. Can we remove
> it without breaking anything else?

IIRC there were/are some drivers that were not terminating the rates[]
array correctly with a -1, thus this code.

> What other options would we have to fix this issue? Just use max_rates = 4 
> in rt2800 even if we will only use the first rate provided by minstrel and
> then fall back to the global fallback setup (I tried that already and it
> works just fine but seems not correct to me)?

p54 kinda does some trickery in this area too, not really sure what to
do though.

johannes