From: Jiri Slaby jslaby@suse.cz
stable inclusion from stable-v5.10.121 commit 10c5088a312dd5311da9e13370629972fe42da88 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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: 3c6a483275f4 (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 Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- 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 a7363bc66c11..351ad0b02029 100644 --- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -628,22 +628,6 @@ 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; @@ -893,9 +877,10 @@ 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--; } @@ -950,9 +935,11 @@ 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--; }