6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Daniel Golle daniel@makrotopia.org
commit d518314a1fa4e980a227d1b2bda1badf433cb932 upstream.
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 e32a83c70cf9 ("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: e32a83c70cf9 ("serial: 8250-mtk: modify mtk uart power and clock management") Fixes: b6c7ff2693ddc ("serial: 8250_mtk: Simplify clock sequencing and runtime PM") Cc: stable stable@kernel.org Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com Signed-off-by: Daniel Golle daniel@makrotopia.org Link: https://patch.msgid.link/de5197ccc31e1dab0965cabcc11ca92e67246cf6.1758058441... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/8250/8250_mtk.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/tty/serial/8250/8250_mtk.c +++ b/drivers/tty/serial/8250/8250_mtk.c @@ -435,6 +435,7 @@ static int __maybe_unused mtk8250_runtim 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_runtim 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 platf 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);