From 575d3966a7da3bdab7a0edc42998453203346cbd Mon Sep 17 00:00:00 2001
From: Tony Lindgren <tony@atomide.com>
Date: Mon, 23 Oct 2023 10:48:54 +0300
Subject: [PATCH] serial: core: Fix runtime PM handling for pending tx
commit 6f699743aebf07538e506a46c5965eb8bdd2c716 upstream.
Richard reported that a serial port may end up sometimes with tx data
pending in the buffer for long periods of time.
Turns out we bail out early on any errors from pm_runtime_get(),
including -EINPROGRESS. To fix the issue, we need to ignore -EINPROGRESS
as we only care about the runtime PM usage count at this point. We check
for an active runtime PM state later on for tx.
Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Cc: stable <stable@kernel.org>
Reported-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Cc: Bruce Ashfield <bruce.ashfield@gmail.com>
Cc: Mikko Rapeli <mikko.rapeli@linaro.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Randy MacLeod <randy.macleod@windriver.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Link: https://lore.kernel.org/r/20231023074856.61896-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/serial_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 83c419ac78bc..0c6c633c0924 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -147,7 +147,7 @@ static void __uart_start(struct tty_struct *tty)
/* Increment the runtime PM usage count for the active check below */
err = pm_runtime_get(&port_dev->dev);
- if (err < 0) {
+ if (err < 0 && err != -EINPROGRESS) {
pm_runtime_put_noidle(&port_dev->dev);
return;
}
--
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