linux-kernel - [PATCH v2 1/1] serial: max310x: Use clock-names property matching to recognize EXTCLK

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Message-Id: <20210723125943.22039-1-andriy.shevchenko@linux.intel.com>
Date:   Fri, 23 Jul 2021 15:59:43 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Jiri Slaby <jirislaby@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Dennis Giaya <dgiaya@...i.edu>
Subject: [PATCH v2 1/1] serial: max310x: Use clock-names property matching to recognize EXTCLK

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@...i.edu>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
v2: added Tested-by tag (Dennis), inverted comparison to leave original flow
 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)
-- 
2.30.2