[PATCH] serial: 8250_bcm2835aux: Fix clock imbalance in PM resume
From: Stefan Wahren <wahrenst@gmx.net>
Date: 2024-08-18 17:50:47
Also in:
linux-serial
Subsystem:
8250/16?50 (and clone uarts) serial driver, the rest, tty layer and serial drivers · Maintainers:
Greg Kroah-Hartman, Linus Torvalds, Jiri Slaby
During review Ulf Hansson discovered a clock imbalance in the recently introduced PM resume code. The driver should enable the clock only in case it has been disabled in suspend before. In order to make the conditions easier to read, refactor this into a separate function. Reported-by: Ulf Hansson <redacted> Closes: https://lore.kernel.org/linux-arm-kernel/CAPDyKFoJh3j8xSeXZ9o031YZLTCDYVA+dgvURuwozjDpU_aauA@mail.gmail.com/ (local) Fixes: 0e1d8780526f ("serial: 8250_bcm2835aux: add PM suspend/resume support") Signed-off-by: Stefan Wahren <wahrenst@gmx.net> --- drivers/tty/serial/8250/8250_bcm2835aux.c | 26 +++++++++++++++++------ 1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c b/drivers/tty/serial/8250/8250_bcm2835aux.c
index 36e2bb34d82b..e6b42ca6151e 100644
--- a/drivers/tty/serial/8250/8250_bcm2835aux.c
+++ b/drivers/tty/serial/8250/8250_bcm2835aux.c@@ -214,17 +214,27 @@ static const struct acpi_device_id bcm2835aux_serial_acpi_match[] = { }; MODULE_DEVICE_TABLE(acpi, bcm2835aux_serial_acpi_match); -static int bcm2835aux_suspend(struct device *dev) +static bool bcm2835aux_can_disable_clock(struct device *dev) { struct bcm2835aux_data *data = dev_get_drvdata(dev); struct uart_8250_port *up = serial8250_get_port(data->line); - serial8250_suspend_port(data->line); - if (device_may_wakeup(dev)) - return 0; + return false; if (uart_console(&up->port) && !console_suspend_enabled) + return false; + + return true; +} + +static int bcm2835aux_suspend(struct device *dev) +{ + struct bcm2835aux_data *data = dev_get_drvdata(dev); + + serial8250_suspend_port(data->line); + + if (!bcm2835aux_can_disable_clock(dev)) return 0; clk_disable_unprepare(data->clk);
@@ -236,9 +246,11 @@ static int bcm2835aux_resume(struct device *dev) struct bcm2835aux_data *data = dev_get_drvdata(dev); int ret; - ret = clk_prepare_enable(data->clk); - if (ret) - return ret; + if (bcm2835aux_can_disable_clock(dev)) { + ret = clk_prepare_enable(data->clk); + if (ret) + return ret; + } serial8250_resume_port(data->line); --
2.34.1