i2c: tegra: Synchronize DMA before termination (8814044f) · Commits · 戴 / test

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:

Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-tegra.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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);

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