From: Dmitry Osipenko <digetx@gmail.com>
Date: Tue, 24 Mar 2020 22:12:17 +0300
Subject: i2c: tegra: Synchronize DMA before termination

Git-commit: a70ff65601f1016cb164d2847e9f370e2ed22b39
Patch-mainline: v5.8-rc1
References: jsc#SLE-15847

DMA transfer could be completed, but CPU (which handles DMA interrupt)
may get too busy and can't handle the interrupt in a timely manner,
despite of DMA IRQ being raised. In this case the DMA state needs to
synchronized before terminating DMA transfer in order not to miss the
DMA transfer completion.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/i2c/busses/i2c-tegra.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 9232038ccb40..7c92e91a1cc2 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1219,6 +1219,15 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
 		time_left = tegra_i2c_wait_completion_timeout(
 				i2c_dev, &i2c_dev->dma_complete, xfer_time);
 
+		/*
+		 * Synchronize DMA first, since dmaengine_terminate_sync()
+		 * performs synchronization after the transfer's termination
+		 * and we want to get a completion if transfer succeeded.
+		 */
+		dmaengine_synchronize(i2c_dev->msg_read ?
+				      i2c_dev->rx_dma_chan :
+				      i2c_dev->tx_dma_chan);
+
 		dmaengine_terminate_sync(i2c_dev->msg_read ?
 					 i2c_dev->rx_dma_chan :
 					 i2c_dev->tx_dma_chan);
-- 
2.26.2