[Bug 255465] Kernel panic with Intel Wireless 4965AGN chip

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=255465

--- Comment #2 from Radosław Chmielarz <radoslaw.chmielarz at emersi.eu> ---
Hi,

Sorry for this, it seems I forgot to add it.

I was looking into the code to figure out where the problem is originating from
and the actual problem turned out to be that I was getting "timeout reading
ROM" error messages at startup, this in turn was causing all the values to be 0
and since the code in ieee80211_get_ratetable() (called from
ieee80211_chan_init()) assumed that the channel value passed in was valid it
was calling panic() to indicate that there is missing implementation for this
device.

I have then drilled down to the code which was reading EEPROM and compared it
with Linux (where the device is working). I had not seen any significant
differences apart from a different timeout handling. After modifying the
timeout the device was successfully initiated.

I own an Intel 4965AGN MM2 with TA: D74676-004 and the measured EEPROM read
time for it with 5 us delay is 60 us and with 1 us delay 25 us. This is larger
than what the current code supports. It's also strange since the code is
already several years old and this particular chip is quite popular (at least
from what I have read). Either this is specific to my hardware setup or the
hardware is not used so often.

I will post a separate email with a patch for adjusted read timeout and timeout
error handling.

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