Since ApolloLake, Intel platforms require signed firmware. On all
Windows platforms the default is to require the Intel production key
be used. But some platforms allow for a community key to be used,
which allows developers to compile/build their own firmware.

In the linux-firmware tree, the default intel/sof path is used for
firmwares signed for the production key, and files signed with the
community key are located in intel/sof/community.

Since we don't have an API to query which key is used on what
platforms, we have to rely on DMI-based quirks.

Developers can bypass this mechanism by setting a kernel 'fw_path'
module parameter. Additional dynamic debug traces are provided to help
debug cases where the wrong file might be used.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200107160840.1524-2-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>