From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
Laxman Dewangan <ldewangan@nvidia.com>,
Wolfram Sang <wsa@the-dreams.de>
Cc: linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org,
Vinod Koul <vkoul@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v1 2/2] i2c: tegra: Synchronize DMA before termination
Date: Thu, 19 Mar 2020 23:11:40 +0300 [thread overview]
Message-ID: <20200319201140.17451-3-digetx@gmail.com> (raw)
In-Reply-To: <20200319201140.17451-1-digetx@gmail.com>
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>
---
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 dabb9223990c..b69a10497cd5 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -1224,6 +1224,15 @@ 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);
--
2.25.1
prev parent reply other threads:[~2020-03-19 20:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 20:11 [PATCH v1 0/2] NVIDIA Tegra I2C synchronization correction Dmitry Osipenko
2020-03-19 20:11 ` [PATCH v1 1/2] i2c: tegra: Better handle case where CPU0 is busy for a long time Dmitry Osipenko
2020-03-19 20:11 ` Dmitry Osipenko [this message]
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