1 ===================== 1 =====================
2 Firmware lookup order 2 Firmware lookup order
3 ===================== 3 =====================
4 4
5 Different functionality is available to enable 5 Different functionality is available to enable firmware to be found.
6 Below is chronological order of how firmware w 6 Below is chronological order of how firmware will be looked for once
7 a driver issues a firmware API call. 7 a driver issues a firmware API call.
8 8
9 * The ''Built-in firmware'' is checked first, 9 * The ''Built-in firmware'' is checked first, if the firmware is present we
10 return it immediately 10 return it immediately
11 * The ''Firmware cache'' is looked at next. If 11 * The ''Firmware cache'' is looked at next. If the firmware is found we
12 return it immediately 12 return it immediately
13 * The ''Direct filesystem lookup'' is performe 13 * The ''Direct filesystem lookup'' is performed next, if found we
14 return it immediately 14 return it immediately
15 * The ''Platform firmware fallback'' is perfor 15 * The ''Platform firmware fallback'' is performed next, but only when
16 firmware_request_platform() is used, if foun 16 firmware_request_platform() is used, if found we return it immediately
17 * If no firmware has been found and the fallba 17 * If no firmware has been found and the fallback mechanism was enabled
18 the sysfs interface is created. After this e 18 the sysfs interface is created. After this either a kobject uevent
19 is issued or the custom firmware loading is 19 is issued or the custom firmware loading is relied upon for firmware
20 loading up to the timeout value. 20 loading up to the timeout value.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.