On Thursday, December 05, 2013 1:21:13 am Justin Hibbits wrote:
> I've been working on the projects/pmac_pmu branch for some time now to
> add suspend/resume as well as CPU speed change for certain PowerPC
> machines, about a year since I created the branch, and now it's stable
> enough that I want to merge it into HEAD, hence this request. However,
> it does touch several drivers, turning them into "early drivers", such
> that they can be initialized, and suspended and resumed at a different
> time.  Saying that, I do need testing from other architectures, to make
> sure I haven't broken anything.
> The technical details:
> To get proper ordering, I've extended the bus_generic_suspend() and
> bus_generic_resume() to do multiple passes.  Devices which cannot be
> enabled or disabled at the current pass level would return an EAGAIN.
> This could possibly cause problems, since it's an addition to an
> existing API rather than a new API to run along side it, so it needs a
> great deal of testing.  It works fine on PowerPC, but I don't have any
> i386/amd64 or sparc64 hardware to test it on, so would like others who
> do to test it.  I don't think that it would impact x86 at all (testing
> is obviously required), because the nexus is not an EARLY_DRIVER_MODULE,
> so all devices would be handled at the same pass.  But, I do know the
> sparc64 has an EARLY_DRIVER_MODULE() nexus, so that will likely be
> impacted.

I have patches to change many x86 drivers to use EARLY_DRIVER_MODULE()

Also, I'm still not a fan of the EAGAIN approach.  I'd rather have a method
in bus_if.m to suspend or resume a single device and to track that a device
is suspended or resumed via a device_t flag or some such. (I think I had
suggested this previously as it would also allow us to have a tool to
suspend/resume individual drivers at runtime apart from a full suspend/resume

John Baldwin
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