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pkg/debian: Temporarily add serial suspend

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Ubuntu mainline repos are currently stuck at v6.5.7. However, our
patches are for v6.5.8+ and have thus dropped the serial suspend fix,
which was added upstream in v6.5.8. So add it to the Debian/Ubuntu
package specific patches for now so that we can still build
Debian/Ubuntu kernel packages.
This commit is contained in:
Maximilian Luz 2023-10-29 02:59:44 +02:00
parent 03b1eb13c3
commit 498802c0e8
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1 changed files with 59 additions and 0 deletions
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59
pkg/debian/kernel/0001-serial-core-Fix-checks-for-tx-runtime-PM-state.patch Normal file
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@ -0,0 +1,59 @@
From 8459746f889d72794c164d18423344686267a451 Mon Sep 17 00:00:00 2001
From: Tony Lindgren <tony@atomide.com>
Date: Thu, 5 Oct 2023 10:56:42 +0300
Subject: [PATCH] serial: core: Fix checks for tx runtime PM state
commit 81a61051e0ce5fd7e09225c0d5985da08c7954a7 upstream.
Maximilian reported that surface_serial_hub serdev tx does not work during
system suspend. During system suspend, runtime PM gets disabled in
__device_suspend_late(), and tx is unable to wake-up the serial core port
device that we use to check if tx is safe to start. Johan summarized the
regression noting that serdev tx no longer always works as earlier when the
serdev device is runtime PM active.
The serdev device and the serial core controller devices are siblings of
the serial port hardware device. The runtime PM usage count from serdev
device does not propagate to the serial core device siblings, it only
propagates to the parent.
In addition to the tx issue for suspend, testing for the serial core port
device can cause an unnecessary delay in enabling tx while waiting for the
serial core port device to wake-up. The serial core port device wake-up is
only needed to flush pending tx when the serial port hardware device was
in runtime PM suspended state.
To fix the regression, we need to check the runtime PM state of the parent
serial port hardware device for tx instead of the serial core port device.
As the serial port device drivers may or may not implement runtime PM, we
need to also add a check for pm_runtime_enabled().
Reported-by: Maximilian Luz <luzmaximilian@gmail.com>
Cc: stable <stable@kernel.org>
Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231005075644.25936-1-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 bf63a045fdc8..83c419ac78bc 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -157,7 +157,7 @@ static void __uart_start(struct tty_struct *tty)
* enabled, serial_port_runtime_resume() calls start_tx() again
* after enabling the device.
*/
- if (pm_runtime_active(&port_dev->dev))
+ if (!pm_runtime_enabled(port->dev) || pm_runtime_active(port->dev))
port->ops->start_tx(port);
pm_runtime_mark_last_busy(&port_dev->dev);
pm_runtime_put_autosuspend(&port_dev->dev);
--
2.42.0