From: Larry Finger <Larry.Finger@lwfinger.net>
To: Felix Fietkau <nbd@openwrt.org>
Cc: wireless <linux-wireless@vger.kernel.org>,
"Martín Ernesto Barreyro" <barreyromartin@gmail.com>,
"Johannes Berg" <johannes@sipsolutions.net>
Subject: Re: Minstrel rate-setting question
Date: Thu, 22 Jan 2009 21:39:19 -0600 [thread overview]
Message-ID: <49793BE7.3020509@lwfinger.net> (raw)
In-Reply-To: <497929C1.9060804@openwrt.org>
Felix Fietkau wrote:
> I believe that it's not minstrel's fault. According to the information that
> I have about RTL8187L, the chip implements rate fallback. If the chip changes
> rates during retransmissions, the status information the way you gather it
> will not be accurate and will trick minstrel into believing that higher rates
> actually work (which in fact they don't).
> Please do some transmissions at 54M and run a monitor mode capture on a different
> card to see if it changes the rate during transmission and how frequently it
> uses one rate before falling back (if indeed my theory is correct).
> This information could be used to provide some more accurate feedback through
> multi-rate retry status information.
I believe you have the clue. There is a register named RATE_FALLBACK
and a bit called RTL818X_RATE_FALLBACK_ENABLE. I'm testing a patch
that leaves this bit unset.
Thanks,
Larry
prev parent reply other threads:[~2009-01-23 3:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
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2009-01-23 0:16 ` Minstrel rate-setting question Larry Finger
2009-01-23 2:21 ` Felix Fietkau
2009-01-23 3:39 ` Larry Finger [this message]
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