thunderbolt: Make software margining error counter configurable

The debugfs software margining run path currently initializes the
request with USB4_MARGIN_SW_ERROR_COUNTER_CLEAR, which implicitly
clears/enables counters every time software margining is started.

On some host-router/firmware implementations that enforce PHY
interface for USB4 (PIPE) margining control, CLEAR and START are
distinct operations.
- CLEAR resets error counters without starting margining
- START begins margin testing and error counting

Make the error counter operation configurable through debugfs
error_counter control instead of hardcoding CLEAR. Additionally,
only execute the software margining sampling loop when the
selected operation is START; for CLEAR or STOP operations, execute
the counter operation and return immediately.

Example to CLEAR error counter:
cd /sys/kernel/debug/thunderbolt/<ROUTER_ID>/<PORT>/margining
echo clear > error_counter

Example to START error counter:
cd /sys/kernel/debug/thunderbolt/<ROUTER_ID>/<PORT>/margining
echo start > error_counter

After configuring error counter run software margining for changes
to take effect:
echo 1 > run

This aligns the debugfs behavior with the USB4 v2/PIPE expectation
and lets users explicitly choose between CLEAR/START/STOP.

Co-developed-by: Rene Sapiens <rene.sapiens@linux.intel.com>
Signed-off-by: Rene Sapiens <rene.sapiens@linux.intel.com>
Signed-off-by: Anurag <anurag@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

0 files changed, 0 insertions, 0 deletions