thunderbolt: Add support for receiver lane margining
USB4 spec defines standard set of registers to be used for receiver lane
margining. This is useful for I/O interface quality and electrical
robustness validation during manufacturing. Expose receiver lane
margining through new debugfs directory "margining" that is added under
each connected USB4 port. Users can then run the margining by writing to
the exposed attributes under that directory.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
diff --git a/drivers/thunderbolt/Kconfig b/drivers/thunderbolt/Kconfig
index e76a6c1..d76ba4f 100644
--- a/drivers/thunderbolt/Kconfig
+++ b/drivers/thunderbolt/Kconfig
@@ -27,6 +27,16 @@
Only enable this if you know what you are doing! Never enable
this for production systems or distro kernels.
+config USB4_DEBUGFS_MARGINING
+ bool "Expose receiver lane margining operations under USB4 ports (DANGEROUS)"
+ depends on DEBUG_FS
+ depends on USB4_DEBUGFS_WRITE
+ help
+ Enables hardware and software based receiver lane margining support
+ under each USB4 port. Used for electrical quality and robustness
+ validation during manufacturing. Should not be enabled by distro
+ kernels.
+
config USB4_KUNIT_TEST
bool "KUnit tests" if !KUNIT_ALL_TESTS
depends on (USB4=m || KUNIT=y)
