serial: core: Fix runtime PM handling for pending tx
authorTony Lindgren <tony@atomide.com>
Mon, 23 Oct 2023 07:48:54 +0000 (10:48 +0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 8 Nov 2023 10:56:24 +0000 (11:56 +0100)
commitf1125301091a2bbdca0562fdc70a2482c8fcca24
treebe67b3f03c10eba80a271625f29ec183c644b7c0
parentbe3e3ab567b77fbf49e61fc7cea2fff84540de97
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