linux-kernel - [PATCH 4.19 052/125] Revert "ath10k: fix DMA related firmware crashes on multiple devices"

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Message-Id: <20200901150937.100789081@linuxfoundation.org>
Date:   Tue,  1 Sep 2020 17:10:07 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zhi Chen <zhichen@...eaurora.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 052/125] Revert "ath10k: fix DMA related firmware crashes on multiple devices"

From: Zhi Chen <zhichen@...eaurora.org>

[ Upstream commit a1769bb68a850508a492e3674ab1e5e479b11254 ]

This reverts commit 76d164f582150fd0259ec0fcbc485470bcd8033e.
PCIe hung issue was observed on multiple platforms. The issue was reproduced
when DUT was configured as AP and associated with 50+ STAs.

For QCA9984/QCA9888, the DMA_BURST_SIZE register controls the AXI burst size
of the RD/WR access to the HOST MEM.
0 - No split , RAW read/write transfer size from MAC is put out on bus
    as burst length
1 - Split at 256 byte boundary
2,3 - Reserved

With PCIe protocol analyzer, we can see DMA Read crossing 4KB boundary when
issue happened. It broke PCIe spec and caused PCIe stuck. So revert
the default value from 0 to 1.

Tested:  IPQ8064 + QCA9984 with firmware 10.4-3.10-00047
         QCS404 + QCA9984 with firmware 10.4-3.9.0.2--00044
         Synaptics AS370 + QCA9888  with firmware 10.4-3.9.0.2--00040

Signed-off-by: Zhi Chen <zhichen@...eaurora.org>
Signed-off-by: Kalle Valo <kvalo@...eaurora.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/ath/ath10k/hw.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/hw.h b/drivers/net/wireless/ath/ath10k/hw.h
index fac58c3c576a2..3ff65a0a834a2 100644
--- a/drivers/net/wireless/ath/ath10k/hw.h
+++ b/drivers/net/wireless/ath/ath10k/hw.h
@@ -753,7 +753,7 @@ ath10k_rx_desc_get_l3_pad_bytes(struct ath10k_hw_params *hw,
 
 #define TARGET_10_4_TX_DBG_LOG_SIZE		1024
 #define TARGET_10_4_NUM_WDS_ENTRIES		32
-#define TARGET_10_4_DMA_BURST_SIZE		0
+#define TARGET_10_4_DMA_BURST_SIZE		1
 #define TARGET_10_4_MAC_AGGR_DELIM		0
 #define TARGET_10_4_RX_SKIP_DEFRAG_TIMEOUT_DUP_DETECTION_CHECK 1
 #define TARGET_10_4_VOW_CONFIG			0
-- 
2.25.1