From: Tony Lindgren <tony@atomide.com> stable inclusion from stable-v6.6.1 commit f1125301091a2bbdca0562fdc70a2482c8fcca24 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8IKRU Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- 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 d5ba6e90bd95..f912f8bf1e63 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -146,7 +146,7 @@ static void __uart_start(struct uart_state *state) /* 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; } -- 2.20.1