Hi
On Sunday 10 April 2011, Anton Ivanov wrote:
On 04/10/11 16:23, Stefan Lippers-Hollmann wrote:
Hi
On Sunday 10 April 2011, Anton Ivanov wrote:
On 04/10/11 00:55, Ben Hutchings wrote:
On Fri, 2011-04-08 at 13:39 +0100, Anton Ivanov wrote:
[...]
Yes. No effect. ath still reads from eeprom.
The EEPROM settings are authoritative, you can only restrict the
regulatory settings further to aid regulatory compliance in different
regions, but never relax them. Tools like crda always intersect the
EEPROM's (OTP in newer chipset generations) with the chosen regulatory
domain as provided by wireless-regdb or the in-kernel regdb; regulatory
hints like IEEE 802.11d may also restrict the allowed frequencies even
further.
http://wireless.kernel.org/en/users/Drivers/ath#Regulatory
This is intended beaviour and required for FCC compliance (keep in mind
that calibration data is also only validated for the given regdomain),
not a bug.
So a card that returns only CN from EEPROM is basically intended to be
sold _ONLY_ in China. Right?
[...]
Correct, it's arguably even illegal to sell in ETSI regions. Although
it's technically a little more complex as Atheros groups regdom regions
with identical mappings together[1], which makes reading the EEPROM
based regulatory domain code a bit strange (the alphabetically first
match corresponding to the regdom group gets printed to dmesg).
In your particular case, with a 2.4 GHz-only AR2417 PHY, 0x52
(APL1_WORLD vs ETSI1_WORLD, GB) doesn't actually do any harm, as 'CN'
allows channel 1-13 just as well as the most permissive regdomains
(ch14 in Japan is only allowed for CSMA/CA == 11 MBit/s, not the more
common OFDM rates (>= 54 MBit/s)). So even though your device is
wrongly programmed, it doesn't actually limit your abilities (unless
you'd add an additional 5 GHz capable card, which would suffer from an
'unfortunate' intersection) - and neither allows you to access
non-public frequency bands. This situation would be seriously worse
(both technically and legally) for 5 GHz operations, but your device
doesn't support that anyways.
country CN:
(2402 - 2482 @ 40), (N/A, 20)
(5735 - 5835 @ 40), (N/A, 30)
country GB:
(2402 - 2482 @ 40), (N/A, 20)
(5170 - 5250 @ 40), (N/A, 20)
(5250 - 5330 @ 40), (N/A, 20), DFS
(5490 - 5710 @ 40), (N/A, 27), DFS
However I'm aware of the sad truth that most commonly sold cards are
wrongly programmed for CN or (worse for 2.4 GHz operations) US...
Regards
Stefan Lippers-Hollmann
[1] http://wireless.kernel.org/en/users/Drivers/ath#line-28