The "filter" debugfs file defines the log levels used by
the firmware and reported by sof-logger.

The file contains the formatted entry list, where each entry
follows the following syntax in plain text:
log_level uuid_id pipe_id comp_id;

This file may be updated by userspace applications such sof-logger,
or directly by the user during debugging process.

An unused (wildcard) pipe_id or comp_id value should be set to -1,
uuid_id is hexadecimal value, so when unused then should be set to 0.

When the file is modified, an IPC command is sent to FW with new
trace levels for selected components in filter elements list.
Signed-off-by: Karol Trzcinski <karolx.trzcinski@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20201204165014.2697903-1-kai.vehmanen@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>