This is a note to let you know that I've just added the patch titled
serial: core: Fix runtime PM handling for pending tx
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-core-fix-runtime-pm-handling-for-pending-tx.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6f699743aebf07538e506a46c5965eb8bdd2c716 Mon Sep 17 00:00:00 2001
From: Tony Lindgren <tony@xxxxxxxxxxx>
Date: Mon, 23 Oct 2023 10:48:54 +0300
Subject: serial: core: Fix runtime PM handling for pending tx
From: Tony Lindgren <tony@xxxxxxxxxxx>
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@xxxxxxxxxx>
Reported-by: Richard Purdie <richard.purdie@xxxxxxxxxxxxxxxxxxx>
Cc: Bruce Ashfield <bruce.ashfield@xxxxxxxxx>
Cc: Mikko Rapeli <mikko.rapeli@xxxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Randy MacLeod <randy.macleod@xxxxxxxxxxxxx>
Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
Tested-by: Richard Purdie <richard.purdie@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231023074856.61896-1-tony@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -147,7 +147,7 @@ static void __uart_start(struct tty_stru
/* 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;
}
Patches currently in stable-queue which might be from tony@xxxxxxxxxxx are
queue-6.5/serial-core-fix-runtime-pm-handling-for-pending-tx.patch
