Messages in this thread | | | Date | Fri, 16 Aug 2013 21:00:09 +0100 | From | Mark Brown <> | Subject | Re: Non-enumerable devices on USB and other enumerable buses |
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On Fri, Aug 16, 2013 at 03:27:58PM -0400, Alan Stern wrote: > On Fri, 16 Aug 2013, Mark Brown wrote:
> > or those for getting platform data to a device when it > > does enumerate.
> ? I can't make any sense out of that comment. For one thing, why do > you need to send platform data to a device? (It's obvious that a > _driver_ would need to use platform data; it's not so clear that a > _device_ would.)
The device in this context is a running instance of the driver.
> > > (The second proposal also has the advantage that the power-on code may > > > be shared between the driver and the subsystem.)
> > Can you explain in more detail please, I don't follow?
> Let's say the subsystem powers up the device when the bus is first > registered, so that the device can be detected and enumerated. Let's > also say that the driver wants to power-off and power-on the device > from time to time, as part of normal runtime PM. Then instead of > having its own power-on routine (which would be code duplication), the > driver can simply call the subsystem's power-on routine. (Of course, > this would mean that the routine would no longer be run-once.)
Oh, OK. I don't think that's a meaningful difference, the driver is going to have the code and be able to reuse it one way or another anyway. In many cases if the device has been in a low power idle mode a slightly difference sequence would be needed anyway. [unhandled content-type:application/pgp-signature] | |