[PATCH 1/2] ath10k: skip quiet mode for WCN3990 to prevent firmware crash

[Malte Schababerle <m.schababerle@gmail.com>]

WCN3990 firmware (WLAN.HL.3.2) crashes deterministically when the
quiet mode WMI command is sent during ath10k_start(). The crash occurs
at PC=0xb0008e20 in wlanmdsp.mbn, ~17ms after the subsequent
vdev_create command, and cascades into a full modem crash.

Commit 53884577fbcef ("ath10k: skip sending quiet mode cmd for
WCN3990") addressed this for HL2.0 firmware by gating quiet mode on
WMI_SERVICE_THERM_THROT. HL2.0 did not advertise the service bit, so
the guard was effective. However, newer WCN3990 firmware (HL3.2)
erroneously advertises WMI_SERVICE_THERM_THROT via its TLV service
map despite still being unable to handle the quiet mode command.

Skip quiet mode unconditionally for WCN3990 using QCA_REV_WCN3990()
instead of relying on the service bit.

Tested on OnePlus 7T (SM8150/WCN3990) with WLAN.HL.3.2.0.c2-00006
and WLAN.HL.3.2.0.c2-00011 (both crash without patch, both work with):
- wlan0 comes up without crash
- WiFi scanning works
- NetworkManager recognizes the interface

Fixes: 53884577fbcef ("ath10k: skip sending quiet mode cmd for WCN3990")
Signed-off-by: Malte Schababerle <m.schababerle@gmail.com>
---
 drivers/net/wireless/ath/ath10k/thermal.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/wireless/ath/ath10k/thermal.c b/drivers/net/wireless/ath/ath10k/thermal.c
index 8b15ec07b1071..33f299f414710 100644
--- a/drivers/net/wireless/ath/ath10k/thermal.c
+++ b/drivers/net/wireless/ath/ath10k/thermal.c
@@ -136,6 +136,16 @@ void ath10k_thermal_set_throttling(struct ath10k *ar)
 	if (!ar->wmi.ops->gen_pdev_set_quiet_mode)
 		return;
 
+	/* WCN3990 firmware crashes on quiet mode despite advertising support.
+	 * See also commit 53884577fbcef ("ath10k: skip sending quiet mode
+	 * cmd for WCN3990").
+	 */
+	if (QCA_REV_WCN3990(ar)) {
+		ath10k_dbg(ar, ATH10K_DBG_BOOT,
+			   "skip quiet mode for WCN3990 (known crash trigger)\n");
+		return;
+	}
+
 	if (ar->state != ATH10K_STATE_ON)
 		return;
 
-- 
2.47.3