From 422a2940a0b04fd5bfcf7e29cc9d5941b1ed5e6b Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: Fri, 23 Jul 2021 15:59:43 +0300
Subject: [PATCH] serial: max310x: Use clock-names property matching to recognize EXTCLK
Git-commit: 3d1fa055ea7298345795b982de7a5b9ec6ae238d
Patch-mainline: v5.15-rc1
References: stable-5.14.6

[ Upstream commit 3d1fa055ea7298345795b982de7a5b9ec6ae238d ]

Dennis reported that on ACPI-based systems the clock frequency
isn't enough to configure device properly. We have to respect
the clock source as well. To achieve this match the clock-names
property against "osc" to recognize external clock connection.
On DT-based system this doesn't change anything.

Reported-and-tested-by: Dennis Giaya <dgiaya@whoi.edu>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210723125943.22039-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/tty/serial/max310x.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index ef11860cd69e..3df0788ddeb0 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -1271,18 +1271,13 @@ static int max310x_probe(struct device *dev, const struct max310x_devtype *devty
 	/* Always ask for fixed clock rate from a property. */
 	device_property_read_u32(dev, "clock-frequency", &uartclk);
 
-	s->clk = devm_clk_get_optional(dev, "osc");
+	xtal = device_property_match_string(dev, "clock-names", "osc") < 0;
+	if (xtal)
+		s->clk = devm_clk_get_optional(dev, "xtal");
+	else
+		s->clk = devm_clk_get_optional(dev, "osc");
 	if (IS_ERR(s->clk))
 		return PTR_ERR(s->clk);
-	if (s->clk) {
-		xtal = false;
-	} else {
-		s->clk = devm_clk_get_optional(dev, "xtal");
-		if (IS_ERR(s->clk))
-			return PTR_ERR(s->clk);
-
-		xtal = true;
-	}
 
 	ret = clk_prepare_enable(s->clk);
 	if (ret)
-- 
2.26.2