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[v2,1/2] wifi: mt76: mt7921e: improve reliability of dma reset

Message ID bd53c5cf67a5a1cac3e94713704a5dc4e17431c9.1681333416.git.objelf@gmail.com
State New
Headers show
Series [v2,1/2] wifi: mt76: mt7921e: improve reliability of dma reset | expand

Commit Message

Sean Wang April 12, 2023, 9:11 p.m. UTC 
From: Quan Zhou <quan.zhou@mediatek.com>

The hardware team has advised the driver that it is necessary to first put
WFDMA into an idle state before resetting the WFDMA. Otherwise, the WFDMA
may enter an unknown state where it cannot be polled with the right state
successfully. To ensure that the DMA can work properly while a stressful
cold reboot test was being made, we have reordered the programming sequence
in the driver based on the hardware team's guidance.

The patch would modify the WFDMA disabling flow from

"DMA reset -> disabling DMASHDL -> disabling WFDMA -> polling and waiting
until DMA idle" to "disabling WFDMA -> polling and waiting for DMA idle ->
disabling DMASHDL -> DMA reset.

Where he polling and waiting until WFDMA is idle is coordinated with the
operation of disabling WFDMA. Even while WFDMA is being disabled, it can
still handle Tx/Rx requests. The additional polling allows sufficient time
for WFDMA to process the last T/Rx request. When the idle state of WFDMA is
reached, it is a reliable indication that DMASHDL is also idle to ensure it
is safe to disable it and perform the DMA reset.

Fixes: 0a1059d0f060 ("mt76: mt7921: move mt7921_dma_reset in dma.c")
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Co-developed-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Co-developed-by: Wang Zhao <wang.zhao@mediatek.com>
Signed-off-by: Wang Zhao <wang.zhao@mediatek.com>
Signed-off-by: Quan Zhou <quan.zhou@mediatek.com>
---
v2: update the commit message to ensure that it is consistent between the
    patch content and the documentation. This will help to accurately
    reflect the changes made and make it easier for other developers to
    understand the purpose of the update.
---
 .../net/wireless/mediatek/mt76/mt7921/dma.c   | 36 ++++++++++---------
 1 file changed, 20 insertions(+), 16 deletions(-)
diff mbox series

Patch

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 |