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.