9424a0a456
[ Upstream commit 398cecc24846e867b9f90a0bd22730e3df6b05be ] We must idle the uart only after serial8250_unregister_port(). Otherwise unbinding the uart via sysfs while doing cat on the port produces an imprecise external abort: mem_serial_in from omap_8250_pm+0x44/0xf4 omap_8250_pm from uart_hangup+0xe0/0x194 uart_hangup from __tty_hangup.part.0+0x37c/0x3a8 __tty_hangup.part.0 from uart_remove_one_port+0x9c/0x22c uart_remove_one_port from serial8250_unregister_port+0x60/0xe8 serial8250_unregister_port from omap8250_remove+0x6c/0xd0 omap8250_remove from platform_remove+0x28/0x54 Turns out the driver needs to have runtime PM functional before the driver probe calls serial8250_register_8250_port(). And it needs runtime PM after driver remove calls serial8250_unregister_port(). On probe, we need to read registers before registering the port in omap_serial_fill_features_erratas(). We do that with custom uart_read() already. On remove, after serial8250_unregister_port(), we need to write to the uart registers to idle the device. Let's add a custom uart_write() for that. Currently the uart register access depends on port->membase to be initialized, which won't work after serial8250_unregister_port(). Let's use priv->membase instead, and use it for runtime PM related functions to remove the dependency to port->membase for early and late register access. Note that during use, we need to check for a valid port in the runtime PM related functions. This is needed for the optional wakeup configuration. We now need to set the drvdata a bit earlier so it's available for the runtime PM functions. With the port checks in runtime PM functions, the old checks for priv in omap8250_runtime_suspend() and omap8250_runtime_resume() functions are no longer needed and are removed. Signed-off-by: Tony Lindgren <tony@atomide.com> Link: https://lore.kernel.org/r/20230508082014.23083-3-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Stable-dep-of: 560706eff7c8 ("serial: 8250_omap: Fix errors with no_console_suspend") Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.