e59f294e00
Changes:
- Replace temporary serial-port suspend fix with proper one
- Rebase onto v6.5.6
Links:
- kernel: 52575b42ef
55 lines
2.4 KiB
Diff
55 lines
2.4 KiB
Diff
From 89b8b8c121fe201862929709d451fecb24947676 Mon Sep 17 00:00:00 2001
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From: Tony Lindgren <tony@atomide.com>
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Date: Thu, 5 Oct 2023 10:56:42 +0300
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Subject: [PATCH] serial: core: Fix checks for tx runtime PM state
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Maximilian reported that surface_serial_hub serdev tx does not work during
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system suspend. During system suspend, runtime PM gets disabled in
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__device_suspend_late(), and tx is unable to wake-up the serial core port
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device that we use to check if tx is safe to start. Johan summarized the
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regression noting that serdev tx no longer always works as earlier when the
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serdev device is runtime PM active.
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The serdev device and the serial core controller devices are siblings of
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the serial port hardware device. The runtime PM usage count from serdev
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device does not propagate to the serial core device siblings, it only
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propagates to the parent.
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In addition to the tx issue for suspend, testing for the serial core port
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device can cause an unnecessary delay in enabling tx while waiting for the
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serial core port device to wake-up. The serial core port device wake-up is
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only needed to flush pending tx when the serial port hardware device was
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in runtime PM suspended state.
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To fix the regression, we need to check the runtime PM state of the parent
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serial port hardware device for tx instead of the serial core port device.
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As the serial port device drivers may or may not implement runtime PM, we
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need to also add a check for pm_runtime_enabled().
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Reported-by: Maximilian Luz <luzmaximilian@gmail.com>
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Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM")
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Signed-off-by: Tony Lindgren <tony@atomide.com>
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Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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Patchset: surface-sam
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---
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drivers/tty/serial/serial_core.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
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index 831d033611e6..e429ac42a12e 100644
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--- a/drivers/tty/serial/serial_core.c
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+++ b/drivers/tty/serial/serial_core.c
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@@ -157,7 +157,7 @@ static void __uart_start(struct tty_struct *tty)
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* enabled, serial_port_runtime_resume() calls start_tx() again
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* after enabling the device.
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*/
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- if (pm_runtime_active(&port_dev->dev))
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+ if (!pm_runtime_enabled(port->dev) || pm_runtime_active(port->dev))
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port->ops->start_tx(port);
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pm_runtime_mark_last_busy(&port_dev->dev);
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pm_runtime_put_autosuspend(&port_dev->dev);
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--
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2.42.0
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