[PATCH 1/2] wifi: mt76: mt7921e: improve reliability of dma reset

[Deren Wu]

From: Quan Zhou <quan.zhou at mediatek.com>

We should put dma into idle status before reset the component. Otherwise,
there would be a potential risk to make the dma hang. Let's reorder the
sequence to make sure the HW working properly.

Tested pass with 50000 times cold reboot on x86 platform.

Fixes: 0a1059d0f060 ("mt76: mt7921: move mt7921_dma_reset in dma.c")
Signed-off-by: Quan Zhou <quan.zhou at mediatek.com>
Signed-off-by: Deren Wu <deren.wu at mediatek.com>
---
 .../net/wireless/mediatek/mt76/mt7921/dma.c   | 36 ++++++++++---------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/dma.c b/drivers/net/wireless/mediatek/mt76/mt7921/dma.c
index d1f10f6d9adc..cf844224d618 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/dma.c
@@ -66,22 +66,6 @@ static void mt7921_dma_prefetch(struct mt7921_dev *dev)
 
 static int mt7921_dma_disable(struct mt7921_dev *dev, bool force)
 {
-	if (force) {
-		/* reset */
-		mt76_clear(dev, MT_WFDMA0_RST,
-			   MT_WFDMA0_RST_DMASHDL_ALL_RST |
-			   MT_WFDMA0_RST_LOGIC_RST);
-
-		mt76_set(dev, MT_WFDMA0_RST,
-			 MT_WFDMA0_RST_DMASHDL_ALL_RST |
-			 MT_WFDMA0_RST_LOGIC_RST);
-	}
-
-	/* disable dmashdl */
-	mt76_clear(dev, MT_WFDMA0_GLO_CFG_EXT0,
-		   MT_WFDMA0_CSR_TX_DMASHDL_ENABLE);
-	mt76_set(dev, MT_DMASHDL_SW_CONTROL, MT_DMASHDL_DMASHDL_BYPASS);
-
 	/* disable WFDMA0 */
 	mt76_clear(dev, MT_WFDMA0_GLO_CFG,
 		   MT_WFDMA0_GLO_CFG_TX_DMA_EN | MT_WFDMA0_GLO_CFG_RX_DMA_EN |
@@ -95,6 +79,22 @@ static int mt7921_dma_disable(struct mt7921_dev *dev, bool force)
 		       MT_WFDMA0_GLO_CFG_RX_DMA_BUSY, 0, 1000))
 		return -ETIMEDOUT;
 
+	/* disable dmashdl */
+	mt76_clear(dev, MT_WFDMA0_GLO_CFG_EXT0,
+		   MT_WFDMA0_CSR_TX_DMASHDL_ENABLE);
+	mt76_set(dev, MT_DMASHDL_SW_CONTROL, MT_DMASHDL_DMASHDL_BYPASS);
+
+	if (force) {
+		/* reset */
+		mt76_clear(dev, MT_WFDMA0_RST,
+			   MT_WFDMA0_RST_DMASHDL_ALL_RST |
+			   MT_WFDMA0_RST_LOGIC_RST);
+
+		mt76_set(dev, MT_WFDMA0_RST,
+			 MT_WFDMA0_RST_DMASHDL_ALL_RST |
+			 MT_WFDMA0_RST_LOGIC_RST);
+	}
+
 	return 0;
 }
 
@@ -301,6 +301,10 @@ void mt7921_dma_cleanup(struct mt7921_dev *dev)
 		   MT_WFDMA0_GLO_CFG_OMIT_RX_INFO |
 		   MT_WFDMA0_GLO_CFG_OMIT_RX_INFO_PFET2);
 
+	mt76_poll_msec_tick(dev, MT_WFDMA0_GLO_CFG,
+			    MT_WFDMA0_GLO_CFG_TX_DMA_BUSY |
+			    MT_WFDMA0_GLO_CFG_RX_DMA_BUSY, 0, 100, 1);
+
 	/* reset */
 	mt76_clear(dev, MT_WFDMA0_RST,
 		   MT_WFDMA0_RST_DMASHDL_ALL_RST |
-- 
2.18.0