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Commit d92aca3a authored by Jon Hunter's avatar Jon Hunter Committed by Greg Kroah-Hartman
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serial: tegra: Correct shutdown of UARTs 



There are two issues in the shutdown path of the UARTs which are:
1. The function tegra_uart_shutdown() calls tegra_uart_flush_buffer()
   to stop DMA TX transfers. However, tegra_uart_flush_buffer() is
   called after the DMA channels have already been freed and so actually
   does nothing.
2. The function that frees the DMA channels
   (tegra_uart_dma_channel_free()), unmaps the dma buffer before
   freeing the DMA channel and does not ensure the DMA has been
   stopped.

Resolve this by fixing the code in tegra_uart_dma_channel_free() to
ensure the DMA is stopped, free the DMA channel and then unmap the DMA
buffer. Finally, remove the unnecessary call to tegra_uart_flush_buffer().

Signed-off-by: default avatarJon Hunter <jonathanh@nvidia.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 49433c80

drivers/tty/serial/serial-tegra.c

+4 −7
Original line number Original line Diff line number Diff line
@@ -1020,24 +1020,23 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup, 
static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,

static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,

		bool dma_to_memory)

		bool dma_to_memory)

{

{

	struct dma_chan *dma_chan;



	if (dma_to_memory) {

	if (dma_to_memory) {

		dmaengine_terminate_all(tup->rx_dma_chan);

		dma_release_channel(tup->rx_dma_chan);

		dma_free_coherent(tup->uport.dev, TEGRA_UART_RX_DMA_BUFFER_SIZE,

		dma_free_coherent(tup->uport.dev, TEGRA_UART_RX_DMA_BUFFER_SIZE,

				tup->rx_dma_buf_virt, tup->rx_dma_buf_phys);

				tup->rx_dma_buf_virt, tup->rx_dma_buf_phys);

		dma_chan = tup->rx_dma_chan;

		tup->rx_dma_chan = NULL;

		tup->rx_dma_chan = NULL;

		tup->rx_dma_buf_phys = 0;

		tup->rx_dma_buf_phys = 0;

		tup->rx_dma_buf_virt = NULL;

		tup->rx_dma_buf_virt = NULL;

	} else {

	} else {

		dmaengine_terminate_all(tup->tx_dma_chan);

		dma_release_channel(tup->tx_dma_chan);

		dma_unmap_single(tup->uport.dev, tup->tx_dma_buf_phys,

		dma_unmap_single(tup->uport.dev, tup->tx_dma_buf_phys,

			UART_XMIT_SIZE, DMA_TO_DEVICE);

			UART_XMIT_SIZE, DMA_TO_DEVICE);

		dma_chan = tup->tx_dma_chan;

		tup->tx_dma_chan = NULL;

		tup->tx_dma_chan = NULL;

		tup->tx_dma_buf_phys = 0;

		tup->tx_dma_buf_phys = 0;

		tup->tx_dma_buf_virt = NULL;

		tup->tx_dma_buf_virt = NULL;

	}

	}

	dma_release_channel(dma_chan);

}

}





static int tegra_uart_startup(struct uart_port *u)

static int tegra_uart_startup(struct uart_port *u)
@@ -1104,8 +1103,6 @@ static void tegra_uart_shutdown(struct uart_port *u) 
	tegra_uart_dma_channel_free(tup, true);

	tegra_uart_dma_channel_free(tup, true);

	tegra_uart_dma_channel_free(tup, false);

	tegra_uart_dma_channel_free(tup, false);

	free_irq(u->irq, tup);

	free_irq(u->irq, tup);



	tegra_uart_flush_buffer(u);

}

}





static void tegra_uart_enable_ms(struct uart_port *u)

static void tegra_uart_enable_ms(struct uart_port *u)