tty: max310x: Fix external crystal register setup

The datasheet states:

  Bit 4: ClockEnSet the ClockEn bit high to enable an external clocking
(crystal or clock generator at XIN). Set the ClockEn bit to 0 to disable
clocking
  Bit 1: CrystalEnSet the CrystalEn bit high to enable the crystal
oscillator. When using an external clock source at XIN, CrystalEn must
be set low.

The bit 4, MAX310X_CLKSRC_EXTCLK_BIT, should be set and was not.

This was required to make the MAX3107 with an external crystal on our
board able to send or receive data.

Signed-off-by: Joe Burmeister <joe.burmeister@devtank.co.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index 450ba6d7996c..e5aebbf5f302 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -581,7 +581,7 @@ static int max310x_set_ref_clk(struct device *dev, struct max310x_port *s,
         }
 
         /* Configure clock source */
-        clksrc = xtal ? MAX310X_CLKSRC_CRYST_BIT : MAX310X_CLKSRC_EXTCLK_BIT;
+        clksrc = MAX310X_CLKSRC_EXTCLK_BIT | (xtal ? MAX310X_CLKSRC_CRYST_BIT : 0);
 
         /* Configure PLL */
         if (pllcfg) {