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From: James Prestwood <prestwoj@gmail.com>
To: iwd@lists.linux.dev
Cc: James Prestwood <prestwoj@gmail.com>, Keith G <ys3al35l@gmail.com>
Subject: [PATCH] scan: limit COLOCATED_6GHZ flag to 6ghz devices
Date: Wed,  3 Jan 2024 04:56:38 -0800	[thread overview]
Message-ID: <20240103125638.243820-1-prestwoj@gmail.com> (raw)

It was seen that this flag seems to cause issues when in AP mode on
brcmfmac devices (e.g. the raspberry Pi 3). When in AP mode an a
scan is issued clients will disconnect. After testing this behavior
was isolated to the use of the COLOCATED_6GHZ flag.

Besides working around the problem on this specific hardware the
patch itself makes sense as a non-6GHz capable device shouldn't use
this flag anyways.

As stated in the patch comment, this isn't really a catch all
workaround since the flag is still used for devices supporting 6GHz.
If additional hardware exhibits this behavior we may need additional
changes like a hardware blacklist or an explicit option to disable
the flag.

Reported-By: Keith G <ys3al35l@gmail.com>
---
 src/scan.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/scan.c b/src/scan.c
index f48ffdef..8c6fdc08 100644
--- a/src/scan.c
+++ b/src/scan.c
@@ -394,7 +394,20 @@ static struct l_genl_msg *scan_build_cmd(struct scan_context *sc,
 	if (params->ap_scan)
 		flags |= NL80211_SCAN_FLAG_AP;
 
-	flags |= NL80211_SCAN_FLAG_COLOCATED_6GHZ;
+	/*
+	 * TODO: This flag appears to cause some undesired behavior on brcmfmac
+	 *       when the device is in AP mode, or has a secondary AP interface
+	 *       running, causing clients to disconnect when a scan is issued.
+	 *
+	 *       Only using this flag for 6GHz capable devices will limit this
+	 *       behavior to only 6GHz devices and in reality makes sense
+	 *       because a non-6GHz device shouldn't use this flag anyways. If
+	 *       more issues still are seen related to this we may need an
+	 *       explicit workaround, either brcmfmac-specific or a disable
+	 *       option.
+	 */
+	if (wiphy_band_is_disabled(sc->wiphy, BAND_FREQ_6_GHZ) != -ENOTSUP)
+		flags |= NL80211_SCAN_FLAG_COLOCATED_6GHZ;
 
 	if (flags)
 		l_genl_msg_append_attr(msg, NL80211_ATTR_SCAN_FLAGS, 4, &flags);
-- 
2.34.1


             reply	other threads:[~2024-01-03 12:56 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-03 12:56 James Prestwood [this message]
2024-01-03 12:58 ` [PATCH] scan: limit COLOCATED_6GHZ flag to 6ghz devices James Prestwood
2024-01-03 14:57   ` KeithG
2024-01-03 15:01     ` James Prestwood
2024-01-04  2:42       ` KeithG
2024-01-04 12:54         ` James Prestwood
2024-01-04 18:17 ` Denis Kenzior
2024-01-04 20:30   ` James Prestwood

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