[PATCH 5.18 0881/1095] serial: 8250_bcm7271: Save/restore RTS in suspend/resume

Greg Kroah-Hartman
2022-08-15T22:42:24Z

From: Doug Berger <opendmb@gmail.com>

[ Upstream commit 3182efd036c1b955403d131258234896cbd9fbeb ]

Commit 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming
from S2") prevented an early enabling of RTS during resume, but it did
not actively restore the RTS state after resume.

Fixes: 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming from S2")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220714031316.404918-1-f.fainelli@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/8250/8250_bcm7271.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_bcm7271.c b/drivers/tty/serial/8250/8250_bcm7271.c
index 9b878d023dac..8efdc271eb75 100644
--- a/drivers/tty/serial/8250/8250_bcm7271.c
+++ b/drivers/tty/serial/8250/8250_bcm7271.c
@@ -1139,16 +1139,19 @@ static int __maybe_unused brcmuart_suspend(struct device *dev)
struct brcmuart_priv *priv = dev_get_drvdata(dev);
struct uart_8250_port *up = serial8250_get_port(priv->line);
struct uart_port *port = &up->port;
-
- serial8250_suspend_port(priv->line);
- clk_disable_unprepare(priv->baud_mux_clk);
+ unsigned long flags;

/*
* This will prevent resume from enabling RTS before the
- * baud rate has been resored.
+ * baud rate has been restored.
*/
+ spin_lock_irqsave(&port->lock, flags);
priv->saved_mctrl = port->mctrl;
- port->mctrl = 0;
+ port->mctrl &= ~TIOCM_RTS;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ serial8250_suspend_port(priv->line);
+ clk_disable_unprepare(priv->baud_mux_clk);

return 0;
}
@@ -1158,6 +1161,7 @@ static int __maybe_unused brcmuart_resume(struct device *dev)
struct brcmuart_priv *priv = dev_get_drvdata(dev);
struct uart_8250_port *up = serial8250_get_port(priv->line);
struct uart_port *port = &up->port;
+ unsigned long flags;
int ret;

ret = clk_prepare_enable(priv->baud_mux_clk);
@@ -1180,7 +1184,15 @@ static int __maybe_unused brcmuart_resume(struct device *dev)
start_rx_dma(serial8250_get_port(priv->line));
}
serial8250_resume_port(priv->line);
- port->mctrl = priv->saved_mctrl;
+
+ if (priv->saved_mctrl & TIOCM_RTS) {
+ /* Restore RTS */
+ spin_lock_irqsave(&port->lock, flags);
+ port->mctrl |= TIOCM_RTS;
+ port->ops->set_mctrl(port, port->mctrl);
+ spin_unlock_irqrestore(&port->lock, flags);
+ }
+
return 0;
}

--
2.35.1