2022-03-25 18:18:24

by Kartik Rajput

Subject: [PATCH] serial: tegra: Correct error handling sequence

From: kartik <[email protected]>

In the current error handling sequence the driver checks for break
error at the end.

By handling the break error first, we can avoid a situation where the
driver keeps processing the errors which can be caused by an unhandled
break error.

Signed-off-by: kartik <[email protected]>
---
drivers/tty/serial/serial-tegra.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index b6223fa..ba78a02 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -440,7 +440,19 @@ static char tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
char flag = TTY_NORMAL;

if (unlikely(lsr & TEGRA_UART_LSR_ANY)) {
- if (lsr & UART_LSR_OE) {
+ if (lsr & UART_LSR_BI) {
+ /*
+ * Break error
+ * If FIFO read error without any data, reset Rx FIFO
+ */
+ if (!(lsr & UART_LSR_DR) && (lsr & UART_LSR_FIFOE))
+ tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_RCVR);
+ if (tup->uport.ignore_status_mask & UART_LSR_BI)
+ return TTY_BREAK;
+ flag = TTY_BREAK;
+ tup->uport.icount.brk++;
+ dev_dbg(tup->uport.dev, "Got Break\n");
+ } else if (lsr & UART_LSR_OE) {
/* Overrrun error */
flag = TTY_OVERRUN;
tup->uport.icount.overrun++;
@@ -454,18 +466,6 @@ static char tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
flag = TTY_FRAME;
tup->uport.icount.frame++;
dev_dbg(tup->uport.dev, "Got frame errors\n");
- } else if (lsr & UART_LSR_BI) {
- /*
- * Break error
- * If FIFO read error without any data, reset Rx FIFO
- */
- if (!(lsr & UART_LSR_DR) && (lsr & UART_LSR_FIFOE))
- tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_RCVR);
- if (tup->uport.ignore_status_mask & UART_LSR_BI)
- return TTY_BREAK;
- flag = TTY_BREAK;
- tup->uport.icount.brk++;
- dev_dbg(tup->uport.dev, "Got Break\n");
}
uart_insert_char(&tup->uport, lsr, UART_LSR_OE, 0, flag);
}
--
2.7.4

2022-04-16 00:23:54

by Greg Kroah-Hartman

Subject: Re: [PATCH] serial: tegra: Correct error handling sequence

On Thu, Mar 24, 2022 at 02:34:04PM +0530, Kartik wrote:
> From: kartik <[email protected]>
>
> In the current error handling sequence the driver checks for break
> error at the end.
>
> By handling the break error first, we can avoid a situation where the
> driver keeps processing the errors which can be caused by an unhandled
> break error.
>
> Signed-off-by: kartik <[email protected]>

I need a full, legal name that you use to sign documents with. Is that
this name?

> ---
> drivers/tty/serial/serial-tegra.c | 26 +++++++++++++-------------
> 1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
> index b6223fa..ba78a02 100644
> --- a/drivers/tty/serial/serial-tegra.c
> +++ b/drivers/tty/serial/serial-tegra.c
> @@ -440,7 +440,19 @@ static char tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
> char flag = TTY_NORMAL;
>
> if (unlikely(lsr & TEGRA_UART_LSR_ANY)) {
> - if (lsr & UART_LSR_OE) {
> + if (lsr & UART_LSR_BI) {
> + /*
> + * Break error
> + * If FIFO read error without any data, reset Rx FIFO
> + */
> + if (!(lsr & UART_LSR_DR) && (lsr & UART_LSR_FIFOE))
> + tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_RCVR);
> + if (tup->uport.ignore_status_mask & UART_LSR_BI)
> + return TTY_BREAK;
> + flag = TTY_BREAK;
> + tup->uport.icount.brk++;
> + dev_dbg(tup->uport.dev, "Got Break\n");
> + } else if (lsr & UART_LSR_OE) {
> /* Overrrun error */
> flag = TTY_OVERRUN;
> tup->uport.icount.overrun++;
> @@ -454,18 +466,6 @@ static char tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
> flag = TTY_FRAME;
> tup->uport.icount.frame++;
> dev_dbg(tup->uport.dev, "Got frame errors\n");
> - } else if (lsr & UART_LSR_BI) {
> - /*
> - * Break error
> - * If FIFO read error without any data, reset Rx FIFO
> - */
> - if (!(lsr & UART_LSR_DR) && (lsr & UART_LSR_FIFOE))
> - tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_RCVR);
> - if (tup->uport.ignore_status_mask & UART_LSR_BI)
> - return TTY_BREAK;
> - flag = TTY_BREAK;
> - tup->uport.icount.brk++;
> - dev_dbg(tup->uport.dev, "Got Break\n");
> }
> uart_insert_char(&tup->uport, lsr, UART_LSR_OE, 0, flag);
> }

What commit does this fix?

thanks,

greg k-h