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From:   <yhchuang@realtek.com>
To:     <kvalo@codeaurora.org>
CC:     <linux-wireless@vger.kernel.org>, <briannorris@chromium.org>
Subject: [PATCH v2 02/12] rtw88: pci: reset H2C queue indexes in a single write
Date:   Wed, 2 Oct 2019 10:31:18 +0800
Message-ID: <20191002023128.12090-3-yhchuang@realtek.com>
In-Reply-To: <20191002023128.12090-1-yhchuang@realtek.com>
References: <20191002023128.12090-1-yhchuang@realtek.com>
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From: Yan-Hsuan Chuang <yhchuang@realtek.com>

If the driver doesn't reset the host's and device's indexes
in a single write, the indexes will become different in a
short period. And it will confuse the DMA engine, make it
start to process non-existed entries.

Better to Write-1-to-reset the indexes, for the DMA engine
to know that this is a reset of the H2C queue, not a kick
off.

Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
---

v1 -> v2
  - rebase on top of wireless-drivers-next

 drivers/net/wireless/realtek/rtw88/pci.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c
index d90928be663b..509743cfd70a 100644
--- a/drivers/net/wireless/realtek/rtw88/pci.c
+++ b/drivers/net/wireless/realtek/rtw88/pci.c
@@ -457,9 +457,9 @@ static void rtw_pci_reset_buf_desc(struct rtw_dev *rtwdev)
 	/* reset read/write point */
 	rtw_write32(rtwdev, RTK_PCI_TXBD_RWPTR_CLR, 0xffffffff);
 
-	/* rest H2C Queue index */
-	rtw_write32_set(rtwdev, RTK_PCI_TXBD_H2CQ_CSR, BIT_CLR_H2CQ_HOST_IDX);
-	rtw_write32_set(rtwdev, RTK_PCI_TXBD_H2CQ_CSR, BIT_CLR_H2CQ_HW_IDX);
+	/* reset H2C Queue index in a single write */
+	rtw_write32_set(rtwdev, RTK_PCI_TXBD_H2CQ_CSR,
+			BIT_CLR_H2CQ_HOST_IDX | BIT_CLR_H2CQ_HW_IDX);
 }
 
 static void rtw_pci_reset_trx_ring(struct rtw_dev *rtwdev)
-- 
2.17.1