From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: [PATCH 5/5] i2c: tegra: Synchronize DMA before termination Date: Wed, 6 May 2020 21:33:58 +0200 Message-ID: <20200506193358.2807244-6-thierry.reding@gmail.com> References: <20200506193358.2807244-1-thierry.reding@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200506193358.2807244-1-thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: Dmitry Osipenko , Jon Hunter , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org From: Dmitry Osipenko 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 Signed-off-by: Thierry Reding --- 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 d504e272d9fa..4cee596a604d 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); -- 2.24.1