Re: [PATCH v2] serial: tegra: Read DMA status before terminating

Ilpo Järvinen
2022-10-19T10:19:05Z

[-- Attachment #1: Type: text/plain, Size: 1767 bytes --]

On Tue, 18 Oct 2022, Kartik wrote:

> 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")
>
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> Signed-off-by: Kartik <kkartik@nvidia.com>
> ---
> v1->v2:
> * Pause the DMA before reading the DMA status.
> * Updated commit message.
>
> 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 b7170cb9a544..cda9cd4fa92c 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;

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

--
i.