Commit d518314a authored by Daniel Golle's avatar Daniel Golle Committed by Greg Kroah-Hartman
Browse files

serial: 8250_mtk: Enable baud clock and manage in runtime PM 



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.

Request the baud clock to be prepared and enabled during probe, and to
restore run-time power management capabilities to what it was before commit
e32a83c7 ("serial: 8250-mtk: modify mtk uart power and clock
management") disable and unprepare the baud clock when suspending the UART,
prepare and enable it again when resuming it.

Fixes: e32a83c7 ("serial: 8250-mtk: modify mtk uart power and clock management")
Fixes: b6c7ff26 ("serial: 8250_mtk: Simplify clock sequencing and runtime PM")
Cc: stable <stable@kernel.org>
Reviewed-by: default avatarAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: default avatarDaniel Golle <daniel@makrotopia.org>
Link: https://patch.msgid.link/de5197ccc31e1dab0965cabcc11ca92e67246cf6.1758058441.git.daniel@makrotopia.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent daeb4037

drivers/tty/serial/8250/8250_mtk.c

+4 −2
Original line number Diff line number Diff line
@@ -435,6 +435,7 @@ static int __maybe_unused mtk8250_runtime_suspend(struct device *dev) 
	while

		(serial_in(up, MTK_UART_DEBUG0));



	clk_disable_unprepare(data->uart_clk);

	clk_disable_unprepare(data->bus_clk);



	return 0;
@@ -445,6 +446,7 @@ static int __maybe_unused mtk8250_runtime_resume(struct device *dev) 
	struct mtk8250_data *data = dev_get_drvdata(dev);



	clk_prepare_enable(data->bus_clk);

	clk_prepare_enable(data->uart_clk);



	return 0;

}
@@ -475,13 +477,13 @@ 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);