Unravelling How Firmware Interacts with the Linux Subsystem
summary
Explains how the Linux firmware API actually behaves: synchronous calls like request_firmware block, asynchronous request_firmware_nowait uses callbacks and is preferred to avoid boot delays, and request_firmware_into_buf loads into a caller buffer. Describes the firmware cache criteria (set when async + uevent), timeout defaults (60s, reduced to 10s during suspend), CSFS sysfs fallback via kobject uevent, custom and EFI fallbacks, and walks the Exynos MFC driver path showing request→assign→set_page_data working end to end.
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chapters (11)
- 0:00Start
- 1:09Types of Firmware Request Synchronous
- 4:13Synchronous Firmware Request
- 11:10Firmware Cache
- 14:07Special optimizations on reboot
- 15:00Firmware Search Path
- 17:32Built-in Firmware
- 29:59FALLBACK MECHANISM: CUSTOM
- 33:50FALLBACK MECHANISM TIMEOUT
- 34:42Firmware Lookup Order
- 36:05Example using MFC Device Driver
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