[PATCH 3.16 13/87] tty: max310x: Fix external crystal register setup

From: Ben Hutchings
Date: Wed Oct 02 2019 - 15:13:56 EST


3.16.75-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Joe Burmeister <joe.burmeister@xxxxxxxxxxxxx>

commit 5d24f455c182d5116dd5db8e1dc501115ecc9c2c upstream.

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@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/max310x.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -568,7 +568,7 @@ static int max310x_set_ref_clk(struct ma
}

/* 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) {