On Tue, Dec 13, 2016 at 08:26:41AM +0100, Rafał Miłecki wrote: > On 12/13/2016 04:08 AM, Luis R. Rodriguez wrote: > > Understanding this code is getting out of control without any > > notes. Give the firmware_class driver a much needed documentation love, > > and while at it convert it to the new sphinx documentation format. > > It does help to understand the class/API, thank you!
Glad it is helping! > > +Even if you have these needs there are a few reasons why you may not be > > +able to make use of built-in firmware: > > + > > +* Legalese - firmware is non-GPL compatible > > +* Some firmware may be optional > > +* Firmware upgrades are possible, therefore a new firmware would implicate > > + a complete firmware rebuild. > > Could it be you meant "kernel rebuild" or "vmlinux rebuild" here? Heh, yes... thanks, fixed! > > diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst > > b/Documentation/driver-api/firmware/fallback-mechanisms.rst > > new file mode 100644 > > index 000000000000..edce1d76ce29 > > --- /dev/null > > +++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst > > @@ -0,0 +1,195 @@ > > +=================== > > +Fallback mechanisms > > +=================== > > + > > +A fallback mechanism is supported to allow to overcome failures to do a > > direct > > +filesystem lookup on the root filesystem or when the firmware simply > > cannot be > > +installed for practical reasons on the root filesystem. The kernel > > +configuration options related to supporting the firmware fallback > > mechanism are: > > + > > + * CONFIG_FW_LOADER_USER_HELPER: enables building the firmware fallback > > + mechanism. Most distributions enable this option today. If enabled but > > + CONFIG_FW_LOADER_USER_HELPER_FALLBACK is disabled, only the custom > > fallback > > + mechanism is available and for the request_firmware_nowait() call. > > + * CONFIG_FW_LOADER_USER_HELPER_FALLBACK: force enables each request to > > + enable the kobject uevent fallback mechanism on all firmare API calls > > + except request_firmware_direct(). Most distributions disable this > > option > > + today. The call request_firmware_nowait() allows for one alternative > > + fallback mechanism: if this kconfig option is enabled and your second > > + argument to request_firmware_nowait(), uevent, is set to false you are > > + informing the kernel that you have a custom fallback mechanism and it > > will > > + manually load the firmware. Read below for more details. > > Yeah, it really asks for API simplification ;) So up next once this is done is the new revamp with an extensible firmware API. Luis
