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: Jon Hunter <jonathanh@xxxxxxxxxx>
---
drivers/tty/serial/serial-tegra.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index 987c05665e62..96378da9aefc 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -1020,24 +1020,23 @@ scrub:
static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,
bool dma_to_memory)
{
- struct dma_chan *dma_chan;
-
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,
tup->rx_dma_buf_virt, tup->rx_dma_buf_phys);
- dma_chan = tup->rx_dma_chan;
tup->rx_dma_chan = NULL;
tup->rx_dma_buf_phys = 0;
tup->rx_dma_buf_virt = NULL;
} 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,
UART_XMIT_SIZE, DMA_TO_DEVICE);
- dma_chan = tup->tx_dma_chan;
tup->tx_dma_chan = NULL;
tup->tx_dma_buf_phys = 0;
tup->tx_dma_buf_virt = NULL;
}
- dma_release_channel(dma_chan);
}
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, false);
free_irq(u->irq, tup);
-
- tegra_uart_flush_buffer(u);
}
static void tegra_uart_enable_ms(struct uart_port *u)
--
1.9.1
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