serial: tegra: Read DMA status before terminating

[ Upstream commit 109a951a9f1fd8a34ebd1896cbbd5d5cede880a7 ]

Read the DMA status before terminating the DMA, as doing so deletes
the DMA desc.

Also, to get the correct transfer status information, pause the DMA
using dmaengine_pause() before reading the DMA status.

Fixes: e9ea096dd225 ("serial: tegra: add serial driver")
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Signed-off-by: Kartik <kkartik@nvidia.com>
Link: https://lore.kernel.org/r/1666105086-17326-1-git-send-email-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index b7170cb..cda9cd4 100644 (file)
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -619,8 +619,9 @@ static void tegra_uart_stop_tx(struct uart_port *u)
        if (tup->tx_in_progress != TEGRA_UART_TX_DMA)
                return;
 
-       dmaengine_terminate_all(tup->tx_dma_chan);
+       dmaengine_pause(tup->tx_dma_chan);
        dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
+       dmaengine_terminate_all(tup->tx_dma_chan);
        count = tup->tx_bytes_requested - state.residue;
        async_tx_ack(tup->tx_dma_desc);
        uart_xmit_advance(&tup->uport, count);
@@ -763,8 +764,9 @@ static void tegra_uart_terminate_rx_dma(struct tegra_uart_port *tup)
                return;
        }
 
-       dmaengine_terminate_all(tup->rx_dma_chan);
+       dmaengine_pause(tup->rx_dma_chan);
        dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
+       dmaengine_terminate_all(tup->rx_dma_chan);
 
        tegra_uart_rx_buffer_push(tup, state.residue);
        tup->rx_dma_active = false;