From 87714bf6ed1589813e473db5471e6e9857755764 Mon Sep 17 00:00:00 2001
From: Quan Zhou <quan.zhou@mediatek.com>
Date: Thu, 13 Apr 2023 05:11:13 +0800
Subject: [PATCH] wifi: mt76: mt7921e: improve reliability of dma reset
Git-commit: 87714bf6ed1589813e473db5471e6e9857755764
Patch-mainline: v6.4-rc1
References: git-fixes
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>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
.../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 28207172c4ef..f0a80c2b476a 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, 100, 1))
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 |
--
2.35.3