[PATCH 6.12 141/567] serial: sprd: Return -EPROBE_DEFER when uart clock is not ready

Greg Kroah-Hartman
2026-01-06T17:23:49Z

From: Wenhua Lin <Wenhua.Lin@unisoc.com>

[ Upstream commit 29e8a0c587e328ed458380a45d6028adf64d7487 ]

In sprd_clk_init(), when devm_clk_get() returns -EPROBE_DEFER
for either uart or source clock, we should propagate the
error instead of just warning and continuing with NULL clocks.

Currently the driver only emits a warning when clock acquisition
fails and proceeds with NULL clock pointers. This can lead to
issues later when the clocks are actually needed. More importantly,
when the clock provider is not ready yet and returns -EPROBE_DEFER,
we should return this error to allow deferred probing.

This change adds explicit checks for -EPROBE_DEFER after both:
1. devm_clk_get(uport->dev, uart)
2. devm_clk_get(uport->dev, source)

When -EPROBE_DEFER is encountered, the function now returns
-EPROBE_DEFER to let the driver framework retry probing
later when the clock dependencies are resolved.

Signed-off-by: Wenhua Lin <Wenhua.Lin@unisoc.com>
Link: https://patch.msgid.link/20251022030840.956589-1-Wenhua.Lin@unisoc.com
Reviewed-by: Cixi Geng <cixi.geng@linux.dev>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/sprd_serial.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index 3fc54cc02a1f..c575c38b513d 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -1109,6 +1109,9 @@ static int sprd_clk_init(struct uart_port *uport)

clk_uart = devm_clk_get(uport->dev, "uart");
if (IS_ERR(clk_uart)) {
+ if (PTR_ERR(clk_uart) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+
dev_warn(uport->dev, "uart%d can't get uart clock\n",
uport->line);
clk_uart = NULL;
@@ -1116,6 +1119,9 @@ static int sprd_clk_init(struct uart_port *uport)

clk_parent = devm_clk_get(uport->dev, "source");
if (IS_ERR(clk_parent)) {
+ if (PTR_ERR(clk_parent) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+
dev_warn(uport->dev, "uart%d can't get source clock\n",
uport->line);
clk_parent = NULL;
--
2.51.0