Cc: Pavel Machek <pavel@...>, Rafael J. Wysocki <rjw@...>, Matthew Garrett <mjg59@...>, pm list <linux-pm@...>, LKML <linux-kernel@...>, Nigel Cunningham <nigel@...>, Alan Stern <stern@...>
I don't believe that it is impossible. What is needed is some
thought, and maybe a loose spec.
We need to think about safe ways of solving a simple problem: what to
do when userspace is unable to respond to a kernel uevent request. We
now have a timeout, whether it be handled synchronously or in the
background. I don't think either solution is good enough.
[RFC] Possible Plan:
1) request_firmware() should stick around unmodified but be marked
__deprecated.
2) request_firmware_nowait() as it stands should probably be removed.
After all, it only has 2 in-kernel users at the moment.
3) uevent interface should be notified when userspace handlers are /
are not available so that events can be queued to be handled when
userspace does turn up and re-register a hotplug event handler.
4) request_firmware_async() introduced: asynchronous firmware loading
interface built on basis of 3, such that problems at early boot and
suspend / resume are avoided. Also request_firmware_async() taught to
retain firmware in memory by default such that subsequent calls do
not require a call to userspace if userspace is unavailable.
6) Documentation on correct firmware loading behaviour for driver
authors written, together with migration notes for existing users of
request_firmware().
7) Existing uses of request_firmware() converted.
*Grumble ahead*
Unfortunately, I don't properly understand the uevent interface, so
some of the above may be inaccurate. This is *not* my fault as there
is no decent documentation (and btw, telling me to write the
documentation is not the answer to that problem).
Michael-Luke
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