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USB: serial: cp210x: fix flow-control error handling 

Make sure that the driver crtscts state is not updated in the unlikely
event that the flow-control request fails. Not doing so could break RTS
control.

Fixes: 5951b85088 ("USB: serial: cp210x: suppress modem-control errors")
Cc: stable@vger.kernel.org	# 5.11
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Johan Hovold 2021-07-05 10:20:11 +02:00
parent 2d9a007059
commit ba4bbdabec
1 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/usb/serial/cp210x.c
View File

@ -1190,6 +1190,7 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
struct cp210x_flow_ctl flow_ctl;
u32 flow_repl;
u32 ctl_hs;
bool crtscts;
int ret;
/*
@ -1249,14 +1250,14 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL;
else
flow_repl |= CP210X_SERIAL_RTS_INACTIVE;
port_priv->crtscts = true;
crtscts = true;
} else {
ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE;
if (port_priv->rts)
flow_repl |= CP210X_SERIAL_RTS_ACTIVE;
else
flow_repl |= CP210X_SERIAL_RTS_INACTIVE;
port_priv->crtscts = false;
crtscts = false;
}
if (I_IXOFF(tty)) {
@ -1279,8 +1280,12 @@ static void cp210x_set_flow_control(struct tty_struct *tty,
flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs);
flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);
cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
ret = cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
sizeof(flow_ctl));
if (ret)
goto out_unlock;
port_priv->crtscts = crtscts;
out_unlock:
mutex_unlock(&port_priv->mutex);
}