Messages in this thread | | | From | Michael-Luke Jones <> | Subject | Re: [RFC][PATCH -mm 3/3] PM: Disable _request_firmware before hibernation/suspend | Date | Mon, 28 May 2007 13:26:37 +0100 |
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On 28 May 2007, at 12:51, Kay Sievers wrote:
> Either the whole idea of userspace firmware-loading should be > considered > as a problem impossible to do right because of its unsolvable side > effects. Or at least releasing loaded firmware should be the exception > for drivers which can be sure, that the firmware is not needed in > situations we try to work around here.
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).
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