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62a0ec9dc1
On an Advantech MICA-071 tablet, with a builtin barcode scanner connected to ttyS0, the following message is shown on suspend: serial 00:02: disabled And after suspend/resume trying to use the barcode scanner / ttyS0 shows: serial 00:02: LSR safety check engaged! Indicating that the UARTs io-ports are no longer reachable. This is caused by __pnp_bus_suspend() calling pnp_stop_dev() on the "00:02" pnp device on suspend (this outputs the disabled message). The problem is that pnp_can_write() returns false for the "00:02" pnp device, so after disabling it (disabling its decoding of IO addresses) during suspend, it cannot be re-enabled. Add a pnp_can_write() check to the suspend path and only disable devices which can actually be re-enabled on resume. This fixes the Advantech MICA-071's ttyS0 no longer working after a suspend/resume. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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.