[PATCH 5.4 067/214] Revert "ath10k: fix DMA related firmware crashes on multiple devices"

Greg Kroah-Hartman
2020-09-01T16:24:05Z

From: Zhi Chen <zhichen@codeaurora.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@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.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 2ae57c1de7b55..ae4c9edc445c3 100644
--- a/drivers/net/wireless/ath/ath10k/hw.h
+++ b/drivers/net/wireless/ath/ath10k/hw.h
@@ -810,7 +810,7 @@ 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
--
2.25.1