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serial: pch: don't overwrite xmit->buf[0] by x_char

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commit d9f3af4fbb upstream.

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@vger.kernel.org>
Fixes: 3c6a483275 (Serial: EG20T: add PCH_UART driver)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2022-05-03 10:08:03 +02:00 committed by Greg Kroah-Hartman
parent 1dda32aed6
commit 63b44ffd5c
1 changed files with 7 additions and 20 deletions
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27
drivers/tty/serial/pch_uart.c
View file

@ -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--;
}
@ -946,9 +931,11 @@ 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--;
}