Firmware lookup order¶
Different functionality is available to enable firmware to be found. Below is chronological order of how firmware will be looked for once a driver issues a firmware API call.
The ‘’Built-in firmware’’ is checked first, if the firmware is present we return it immediately
The ‘’Firmware cache’’ is looked at next. If the firmware is found we return it immediately
The ‘’Direct filesystem lookup’’ is performed next, if found we return it immediately
The ‘’Platform firmware fallback’’ is performed next, but only when
firmware_request_platform()is used, if found we return it immediately
If no firmware has been found and the fallback mechanism was enabled the sysfs interface is created. After this either a kobject uevent is issued or the custom firmware loading is relied upon for firmware loading up to the timeout value.