From: stsp <stsp@openbsd.org>
Date: Mon, 6 Nov 2023 08:34:41 +0000 (+0000)
Subject: avoid using MCS9 in iwm(4) Tx rate selection if 40 MHz is disabled
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=93e9809bc90f62da83dce23eb9c99d2d0e7cfd00;p=openbsd

avoid using MCS9 in iwm(4) Tx rate selection if 40 MHz is disabled

MCS9 is not valid on 20HMz so we must not use it in 20MHz-only mode.
Fixes firmware panic 0x00002078, which indicates the driver sets a rate
with a bad number of antennas, bad number of Tx streams, or bad bandwidth.

Observed by dlg@ with the miktrotik AP for which iwm(4) firmware requires
our 20MHz-only workaround to interoperate in 11ac mode.

ok dlg@
---

diff --git a/sys/dev/pci/if_iwm.c b/sys/dev/pci/if_iwm.c
index 2c107ba4b55..fbab94fecb8 100644
--- a/sys/dev/pci/if_iwm.c
+++ b/sys/dev/pci/if_iwm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_iwm.c,v 1.411 2023/10/21 06:41:26 stsp Exp $	*/
+/*	$OpenBSD: if_iwm.c,v 1.412 2023/11/06 08:34:41 stsp Exp $	*/
 
 /*
  * Copyright (c) 2014, 2016 genua gmbh <info@genua.de>
@@ -9294,8 +9294,17 @@ iwm_set_rate_table_vht(struct iwm_node *in, struct iwm_lq_cmd *lqcmd)
 				if (i < 2 && in->in_phyctxt->vht_chan_width >=
 				    IEEE80211_VHTOP0_CHAN_WIDTH_80)
 					tab |= IWM_RATE_MCS_CHAN_WIDTH_80;
-				else
+				else if (in->in_phyctxt->sco ==
+				    IEEE80211_HTOP0_SCO_SCA ||
+				    in->in_phyctxt->sco ==
+				    IEEE80211_HTOP0_SCO_SCB)
 					tab |= IWM_RATE_MCS_CHAN_WIDTH_40;
+				else {
+					/* no 40 MHz, fall back on MCS 8 */
+					tab &= ~IWM_RATE_VHT_MCS_RATE_CODE_MSK;
+					tab |= 8;
+				}
+					
 				tab |= IWM_RATE_MCS_RTS_REQUIRED_MSK;
 				if (i < 4) {
 					if (ieee80211_ra_vht_use_sgi(ni))