fd5c46b754
When we discover existing DP tunnels the code checks whether DP IN adapter port is enabled by calling tb_dp_port_is_enabled() before it continues the discovery process. On Light Ridge (gen 1) controller reading only the first dword of the DP IN config space causes subsequent access to the same DP IN port path config space to fail or return invalid data as can be seen in the below splat: thunderbolt 0000:07:00.0: CFG_ERROR(0:d): Invalid config space or offset Call Trace: tb_cfg_read+0xb9/0xd0 __tb_path_deactivate_hop+0x98/0x210 tb_path_activate+0x228/0x7d0 tb_tunnel_restart+0x95/0x200 tb_handle_hotplug+0x30e/0x630 process_one_work+0x1b4/0x340 worker_thread+0x44/0x3d0 kthread+0xeb/0x120 ? process_one_work+0x340/0x340 ? kthread_park+0xa0/0xa0 ret_from_fork+0x1f/0x30 If both DP In adapter config dwords are read in one go the issue does not reproduce. This is likely firmware bug but we can work it around by always reading the two dwords in one go. There should be no harm for other controllers either so can do it unconditionally. Link: https://lkml.org/lkml/2019/8/28/160 Reported-by: Brad Campbell <lists2009@fnarfbargle.com> Tested-by: Brad Campbell <lists2009@fnarfbargle.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.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.