mt76: mt7915: fix unexpected firmware mode

Avoid firmware falling into spectrum mode since that will set
unexpected PSE/PLE thresholds which lead to Tx hang.

This mode should be cleaned before firmware download stage.
Signed-off-by: Chih-Min Chen <chih-min.chen@mediatek.com>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/init.c

@@ -135,6 +135,12 @@ static int mt7915_init_hardware(struct mt7915_dev *dev)
 
 	set_bit(MT76_STATE_INITIALIZED, &dev->mphy.state);
 
+	/*
+	 * force firmware operation mode into normal state,
+	 * which should be set before firmware download stage.
+	 */
+	mt76_wr(dev, MT_SWDEF_MODE, MT_SWDEF_NORMAL_MODE);
+
 	ret = mt7915_mcu_init(dev);
 	if (ret)
 		return ret;

drivers/net/wireless/mediatek/mt76/mt7915/regs.h

@@ -360,6 +360,13 @@
 #define MT_HIF_REMAP_L2_BASE		GENMASK(31, 12)
 #define MT_HIF_REMAP_BASE_L2		0x00000
 
+#define MT_SWDEF_BASE			0x41f200
+#define MT_SWDEF(ofs)			(MT_SWDEF_BASE + (ofs))
+#define MT_SWDEF_MODE			MT_SWDEF(0x3c)
+#define MT_SWDEF_NORMAL_MODE		0
+#define MT_SWDEF_ICAP_MODE		1
+#define MT_SWDEF_SPECTRUM_MODE		2
+
 #define MT_TOP_BASE			0x18060000
 #define MT_TOP(ofs)			(MT_TOP_BASE + (ofs))