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Commit 77ec584d authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
Browse files

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



commit d9f3af4fbb1d955bbaf872d9e76502f6e3e803cb 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: 3c6a4832 (Serial: EG20T: add PCH_UART driver)
Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220503080808.28332-1-jslaby@suse.cz


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f6cb1470

drivers/tty/serial/pch_uart.c

+7 −20
Original line number Diff line number Diff line
@@ -635,22 +635,6 @@ 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;
@@ -900,9 +884,10 @@ 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--;

	}
@@ -957,9 +942,11 @@ 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--;

	}