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From:   Zhi Chen <zhichen@codeaurora.org>
To:     ath10k@lists.infradead.org
Cc:     linux-wireless@vger.kernel.org, Zhi Chen <zhichen@codeaurora.org>
Subject: [PATCH,v4] Revert "ath10k: fix DMA related firmware crashes on multiple devices"
Date:   Tue, 14 Jan 2020 12:35:21 +0800
Message-Id: <1578976521-6104-1-git-send-email-zhichen@codeaurora.org>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

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@codeaurora.org>
---
v2: restored 10.2 register configuration
v3: modified commit message
v4: resolved conflicts 
---
 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 21b7a2a..775fd62 100644
--- a/drivers/net/wireless/ath/ath10k/hw.h
+++ b/drivers/net/wireless/ath/ath10k/hw.h
@@ -816,7 +816,7 @@ ath10k_is_rssi_enable(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
-- 
2.7.4