linux-kernel - Re: [ath5k-devel] [PATCH] ath5k: fix detection of jumbo frames

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Message-ID: <20081102215218.GA6203@hash.localnet>
Date:	Sun, 2 Nov 2008 16:52:18 -0500
From:	Bob Copeland <me@...copeland.com>
To:	"Luis R. Rodriguez" <lrodriguez@...eros.com>
Cc:	linville@...driver.com, mickflemm@...il.com, jirislaby@...il.com,
	linux-wireless@...r.kernel.org, ath5k-devel@...ts.ath5k.org,
	linux-kernel@...r.kernel.org, michael+ath5k@...pelberg.de
Subject: Re: [ath5k-devel] [PATCH] ath5k: fix detection of jumbo frames

On Sun, Nov 02, 2008 at 01:00:27PM -0800, Luis R. Rodriguez wrote:
> >, and, since
> > 63266a653589e1a237527479f10212ea77ce7844 "ath5k: rates cleanup", we do not fall back to the basic rate, such packets would trigger
> > the following WARN_ON:
> 
> So its slow because using rate 0 takes a while? If indeed you don't
> see a valid use for this rate I'd say to completely disallow it and
> use BUG_ON() on it.

Not sure I follow - these are incoming frames, which all had a status_0
of 0x1a40 (rs_more=0x1000 & length=0xa40).  So hw rate index was zero
on these for some reason, but in my testing the rate index of all other 
packets was something reasonable, e.g. 0x27.  

I looked over the rate tables compared to hal-legacy; I think what we
have now is correct, just the old ath5k code in hw_to_driver_rix would 
set rate=1 for any hw rate index that we didn't know about:

-       /* Something went wrong, fallback to basic rate for this band */
-       if ((mac80211_rix >= sc->curband->n_bitrates) ||
-               (mac80211_rix <= 0 ))
-               mac80211_rix = 1;

That's gone now, and that's why we didn't have the WARN_ON previously.

For TX-side, I think we don't use rate 0 already since Bruno's cleanup,
we should just use the hw_value fields in ath5k_rates which are all 
nonzero.

-- 
Bob Copeland %% www.bobcopeland.com

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