[PATCH] wifi: brcmfmac: keep ARP and ND offload off on the BCM4364

[Andre Eikmeyer <dev@deq.rocks>]

brcmfmac enables the firmware's ARP and IPv6 ND offload (ndoe) whenever
the interface is up and not promiscuous. On the Apple firmware for the
BCM4364, ndoe makes IPv6 downloads collapse. IPv6 downloads topped out
at 55 Mbit/s on a MacBookPro15,1 with the BCM4364/3 and on the
MacBookPro16,1 with the later revision. The BCM4377 is not affected.

macOS enables ND offload for associated sleep only. A trace under
macOS 26.6.1 on a MacBookPro16,2 shows nd_hostip_clear, ndoe=1 and the
IPv6 addresses before sleep and ndoe cleared again on wake, see the
first report below. Keep them off on the BCM4364.

Closes: https://github.com/t2linux/kernel/issues/34
Closes: https://github.com/t2linux/T2-Debian-and-Ubuntu-Kernel/issues/227
Tested-by: Yossef Osman <Yossef.Osman@proton.me>
Tested-by: Aditya Garg <aditya.garg@linux.dev>
Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
---
The KaiT2en community runs this patch with its kernels, no regression
was reported.

 .../net/wireless/broadcom/brcm80211/brcmfmac/core.c    | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
index 92ec269f43b..6eae7135aeb 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
@@ -13,6 +13,7 @@
 #include <net/addrconf.h>
 #include <net/ieee80211_radiotap.h>
 #include <net/ipv6.h>
+#include <brcm_hw_ids.h>
 #include <brcmu_utils.h>
 #include <brcmu_wifi.h>
 
@@ -103,6 +104,15 @@ void brcmf_configure_arp_nd_offload(struct brcmf_if *ifp, bool enable)
 		return;
 	}
 
+	/* With ND offload on while awake, the Apple firmware for the BCM4364
+	 * makes IPv6 downloads drop to low rates. macOS runs ARP and ND
+	 * offload only in sleep, keep both off on this chip.
+	 */
+	if (enable && ifp->drvr->bus_if->chip == BRCM_CC_4364_CHIP_ID) {
+		brcmf_dbg(TRACE, "Skip ARP/ND offload enable on BCM4364\n");
+		enable = false;
+	}
+
 	if (enable)
 		mode = BRCMF_ARP_OL_AGENT | BRCMF_ARP_OL_PEER_AUTO_REPLY;
 	else

base-commit: 991a73f4909f1348ffb4b38765cdb522a775e4c2