This is a note to let you know that I've just added the patch titled
serial: pch: don't overwrite xmit->buf[0] by x_char
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the tty-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From d9f3af4fbb1d955bbaf872d9e76502f6e3e803cb Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@xxxxxxx>
Date: Tue, 3 May 2022 10:08:03 +0200
Subject: serial: pch: don't overwrite xmit->buf[0] by x_char
When x_char is to be sent, the TX path overwrites whatever is in the
circular buffer at offset 0 with x_char and sends it using
pch_uart_hal_write(). I don't understand how this was supposed to work
if xmit->buf[0] already contained some character. It must have been
lost.
Remove this whole pop_tx_x() concept and do the work directly in the
callers. (Without printing anything using dev_dbg().)
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 3c6a483275f4 (Serial: EG20T: add PCH_UART driver)
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Link: https://lore.kernel.org/r/20220503080808.28332-1-jslaby@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/pch_uart.c | 27 +++++++--------------------
1 file changed, 7 insertions(+), 20 deletions(-)
diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index f872613a5e83..6cb631487383 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -624,22 +624,6 @@ static int push_rx(struct eg20t_port *priv, const unsigned char *buf,
return 0;
}
-static int pop_tx_x(struct eg20t_port *priv, unsigned char *buf)
-{
- int ret = 0;
- struct uart_port *port = &priv->port;
-
- if (port->x_char) {
- dev_dbg(priv->port.dev, "%s:X character send %02x (%lu)\n",
- __func__, port->x_char, jiffies);
- buf[0] = port->x_char;
- port->x_char = 0;
- ret = 1;
- }
-
- return ret;
-}
-
static int dma_push_rx(struct eg20t_port *priv, int size)
{
int room;
@@ -889,9 +873,10 @@ static unsigned int handle_tx(struct eg20t_port *priv)
fifo_size = max(priv->fifo_size, 1);
tx_empty = 1;
- if (pop_tx_x(priv, xmit->buf)) {
- pch_uart_hal_write(priv, xmit->buf, 1);
+ if (port->x_char) {
+ pch_uart_hal_write(priv, &port->x_char, 1);
port->icount.tx++;
+ port->x_char = 0;
tx_empty = 0;
fifo_size--;
}
@@ -948,9 +933,11 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
}
fifo_size = max(priv->fifo_size, 1);
- if (pop_tx_x(priv, xmit->buf)) {
- pch_uart_hal_write(priv, xmit->buf, 1);
+
+ if (port->x_char) {
+ pch_uart_hal_write(priv, &port->x_char, 1);
port->icount.tx++;
+ port->x_char = 0;
fifo_size--;
}
--
2.36.0
