From: Kartik <kkartik@nvidia.com>

Date: Tue, 18 Oct 2022 20:28:06 +0530

Subject: serial: tegra: Read DMA status before terminating

Git-commit: 109a951a9f1fd8a34ebd1896cbbd5d5cede880a7

Patch-mainline: v6.2-rc1

References: jsc#PED-1763

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: Matthias Brugger <mbrugger@suse.com>

---

 drivers/tty/serial/serial-tegra.c | 6 ++++--

 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c

index 4304e3f9307dd..e5b9773db5e36 100644

--- a/drivers/tty/serial/serial-tegra.c

+++ b/drivers/tty/serial/serial-tegra.c

@@ -618,8 +618,9 @@ 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);

@@ -762,8 +763,9 @@ 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;

-- 

2.38.1