[PATCH 6.0 0664/1073] serial: tegra: Read DMA status before terminating

Greg Kroah-Hartman
2022-12-28T16:16:19Z

From: Kartik <kkartik@nvidia.com>

[ 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>
---
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 a5748e41483b..ab549b79fde9 100644
--- 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;
--
2.35.1