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From: Daniel Golle <daniel@makrotopia.org>
To: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Jiri Slaby" <jirislaby@kernel.org>,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"AngeloGioacchino Del Regno"
	<angelogioacchino.delregno@collabora.com>,
	"Daniel Golle" <daniel@makrotopia.org>,
	"Uwe Kleine-König" <u.kleine-koenig@baylibre.com>,
	"Yu Jiaoliang" <yujiaoliang@vivo.com>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Changqi Hu" <changqi.hu@mediatek.com>,
	"Sam Shih" <sam.shih@mediatek.com>,
	"Steven Liu" <steven.liu@mediatek.com>,
	"John Crispin" <john@phrozen.org>,
	linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: [PATCH v2 1/2] tty: serial: 8250_mtk: enable baud clock
Date: Mon, 15 Sep 2025 14:06:37 +0100	[thread overview]
Message-ID: <2de07b0a6d51d5d3bf3e55cd03cf75adfc91ee7d.1757941345.git.daniel@makrotopia.org> (raw)

Some MediaTek SoCs got a gated UART baud clock, which currently gets
disabled as the clk subsystem believes it would be unused. This results in
the uart freezing right after "clk: Disabling unused clocks" on those
platforms.

To fix this request the baud clock to be prepared and enabled during probe.

Fixes: e32a83c70cf9 ("serial: 8250-mtk: modify mtk uart power and clock management")
Suggested-by: Sam Shih <sam.shih@mediatek.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
v2: no changes

 drivers/tty/serial/8250/8250_mtk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index b44de2ed7413..9329ed1f759d 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -475,13 +475,13 @@ static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
 	int dmacnt;
 #endif
 
-	data->uart_clk = devm_clk_get(&pdev->dev, "baud");
+	data->uart_clk = devm_clk_get_enabled(&pdev->dev, "baud");
 	if (IS_ERR(data->uart_clk)) {
 		/*
 		 * For compatibility with older device trees try unnamed
 		 * clk when no baud clk can be found.
 		 */
-		data->uart_clk = devm_clk_get(&pdev->dev, NULL);
+		data->uart_clk = devm_clk_get_enabled(&pdev->dev, NULL);
 		if (IS_ERR(data->uart_clk)) {
 			dev_warn(&pdev->dev, "Can't get uart clock\n");
 			return PTR_ERR(data->uart_clk);
-- 
2.51.0

             reply	other threads:[~2025-09-15 13:07 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-15 13:06 Daniel Golle [this message]
2025-09-15 13:06 ` [PATCH v2 2/2] tty: serial: 8250_mtk: manage baud clock in runtime PM ops Daniel Golle
2025-09-15 13:41 ` [PATCH v2 1/2] tty: serial: 8250_mtk: enable baud clock AngeloGioacchino Del Regno
2025-09-15 14:51   ` Andy Shevchenko
2025-09-15 14:54 ` Andy Shevchenko

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