Re: [PATCH] ath11k: Fix ETSI regd with weather radar overlap

From: Kalle Valo <kvalo@codeaurora.org>
To: Sven Eckelmann <sven@narfation.org>
Cc: ath11k@lists.infradead.org, linux-wireless@vger.kernel.org,
	Sven Eckelmann <sven@narfation.org>
Subject: Re: [PATCH] ath11k: Fix ETSI regd with weather radar overlap
Date: Wed, 17 Nov 2021 07:27:37 +0000 (UTC)	[thread overview]
Message-ID: <163713405345.31320.10844437499755849817.kvalo@codeaurora.org> (raw)
In-Reply-To: <20211112153116.1214421-1-sven@narfation.org>

Sven Eckelmann <sven@narfation.org> wrote:

> Some ETSI countries have a small overlap in the wireless-regdb with an ETSI
> channel (5590-5650). A good example is Australia:
> 
>   country AU: DFS-ETSI
>         (2400 - 2483.5 @ 40), (36)
>         (5150 - 5250 @ 80), (23), NO-OUTDOOR, AUTO-BW
>         (5250 - 5350 @ 80), (20), NO-OUTDOOR, AUTO-BW, DFS
>         (5470 - 5600 @ 80), (27), DFS
>         (5650 - 5730 @ 80), (27), DFS
>         (5730 - 5850 @ 80), (36)
>         (57000 - 66000 @ 2160), (43), NO-OUTDOOR
> 
> If the firmware (or the BDF) is shipped with these rules then there is only
> a 10 MHz overlap with the weather radar:
> 
> * below: 5470 - 5590
> * weather radar: 5590 - 5600
> * above: (none for the rule "5470 - 5600 @ 80")
> 
> There are several wrong assumption in the ath11k code:
> 
> * there is always a valid range below the weather radar
>   (actually: there could be no range below the weather radar range OR range
>    could be smaller than 20 MHz)
> * intersected range in the weather radar range is valid
>   (actually: the range could be smaller than 20 MHz)
> * range above weather radar is either empty or valid
>   (actually: the range could be smaller than 20 MHz)
> 
> These wrong assumption will lead in this example to a rule
> 
>   (5590 - 5600 @ 20), (N/A, 27), (600000 ms), DFS, AUTO-BW
> 
> which is invalid according to is_valid_reg_rule() because the freq_diff is
> only 10 MHz but the max_bandwidth is set to 20 MHz. Which results in a
> rejection like:
> 
>   WARNING: at backports-20210222_001-4.4.60-b157d2276/net/wireless/reg.c:3984
>   [...]
>   Call trace:
>   [<ffffffbffc3d2e50>] reg_get_max_bandwidth+0x300/0x3a8 [cfg80211]
>   [<ffffffbffc3d3d0c>] regulatory_set_wiphy_regd_sync+0x3c/0x98 [cfg80211]
>   [<ffffffbffc651598>] ath11k_regd_update+0x1a8/0x210 [ath11k]
>   [<ffffffbffc652108>] ath11k_regd_update_work+0x18/0x20 [ath11k]
>   [<ffffffc0000a93e0>] process_one_work+0x1f8/0x340
>   [<ffffffc0000a9784>] worker_thread+0x25c/0x448
>   [<ffffffc0000aedc8>] kthread+0xd0/0xd8
>   [<ffffffc000085550>] ret_from_fork+0x10/0x40
>   ath11k c000000.wifi: failed to perform regd update : -22
>   Invalid regulatory domain detected
> 
> To avoid this, the algorithm has to be changed slightly. Instead of
> splitting a rule which overlaps with the weather radar range into 3 pieces
> and accepting the first two parts blindly, it must actually be checked for
> each piece whether it is a valid range. And only if it is valid, add it to
> the output array.
> 
> When these checks are in place, the processed rules for AU would end up as
> 
>   country AU: DFS-ETSI
>           (2400 - 2483 @ 40), (N/A, 36), (N/A)
>           (5150 - 5250 @ 80), (6, 23), (N/A), NO-OUTDOOR, AUTO-BW
>           (5250 - 5350 @ 80), (6, 20), (0 ms), NO-OUTDOOR, DFS, AUTO-BW
>           (5470 - 5590 @ 80), (6, 27), (0 ms), DFS, AUTO-BW
>           (5650 - 5730 @ 80), (6, 27), (0 ms), DFS, AUTO-BW
>           (5730 - 5850 @ 80), (6, 36), (N/A), AUTO-BW
> 
> and will be accepted by the wireless regulatory code.
> 
> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Patch applied to ath-next branch of ath.git, thanks.

086c921a3540 ath11k: Fix ETSI regd with weather radar overlap

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20211112153116.1214421-1-sven@narfation.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches