[Ksummit-2011-discuss] My topic suggestions

Grant Likely grant.likely at secretlab.ca
Fri Jul 1 22:12:29 PDT 2011


On Fri, Jul 01, 2011 at 11:00:26PM +0200, Rafael J. Wysocki wrote:
> On Friday, July 01, 2011, Grant Likely wrote:
> > :-)  Yes.  I don't care much about the name either as long as the
> > topics are on the agenda.
> 
> OK
> 
> So what topics exactly (related to the driver core) you'd like to put
> on the agenda? :-)

My big item is how to handle device dependencies outside of the
natural struct device hierarchy.  Such things like an SDHCI controller
depending on inputs on a GPIO controller, or needing both an i2s
device and an spi controlled audio coded to be initialized before
audio can be set up.  The question is how to ensure that all of a
devices dependencies are available before it is probed.

The ASoC folks have a solution for their problem space, but it doesn't
look to be something that can be easily generalized over the whole
kernel.  I've been experimenting with letting drivers 'defer' at
.probe time so that they get called back later.  Right now a lot of
drivers handle it by tweaking initcall levels on the driver, but
that's a nasty hack which does not scale, and doesn't work for
modules.

Second to that, is how to ensure that runtime PM knows about the
dependencies, but that may already be handled simply by the fact that
devices will get references to the resources (GPIO, codec, etc) they
require at boot time and the runtime PM core may already be handling
that.

g.


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