Hi Oliver, Martin.
>> However, I do believe it is still a good idea to provide firmware
>> images from userland instead of having them compiled into the
>> kernel. Not because of some not-even-hypothetical GPL issue but
>> simply to ease maintenance.
> Absolutely. The firmware should be provided by user space. Once,
> upon initial device detection. From then on, everything must be
> purely in kernel.
If we're talking USB here (and in some cases even if we're not), we need
to deal with more than that. Specifically, we need to be able to deal
with the following sequences:
==> Device plugged in and initialised.
Machine suspended.
Device unplugged.
Machine resumed.
==> Device plugged in and initialised.
Machine suspended.
Device unplugged.
Different device plugged in.
Machine resumed.
==> Machine suspended.
Device plugged in.
Machine resumed.
==> Device plugged in and initialised.
Machine suspended.
Device unplugged.
Same device plugged in.
Machine resumed.
The first three sequences means that we can't guarantee that on resume,
the devices available will be identical to those on suspend. The last
sequence means that even if it is, we may need to do more than just
reload firmware - and in the case of notebooks, this sequence is going
to be common. All it needs is for the user to suspend, disconnect
everything to pack it away, get on a plane with it, fly somewhere, plug
it all back in and resume.
Basically, we need to guarantee that on resume, all CURRENTLY PLUGGED IN
hardware gets initialised to a known state, and anything short of that
is just plain buggy. This includes the case where on resume, devices are
found plugged into different ports than on suspend.
Best wishes from Riley.
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