CDF meeting @FOSDEM report

[Marcus Lorentzon]

On 02/12/2013 11:45 PM, Stéphane Marchesin wrote:
>> - Do we need to support chaining several encoders ? We can come up with
>> >  several theoretical use cases, some of them probably exist in real hardware,
>> >  but the details are still a bit fuzzy.
> So, a part which is completely omitted in this thread is how to handle
> suspend/resume ordering. If you have multiple encoders which need to
> be turned on/off in a given order at suspend/resume, how do you handle
> that given the current scheme where they are just separate platform
> drivers in drivers/video?
>
> This problems occurs with drm/exynos in current 3.8 kernels for
> example. On that platform, the DP driver and the FIMD driver will
> suspend/resume in random order, and therefore fail resuming half the
> time. Is there something which could be done in CDF to address that?
My idea here is two parts. First hide the chaining within the CDF 
driver. So it is always the first CDF driver that is responsible for the 
rest of the chain. Second, I'm looking at using the dev->parent and bus 
relationchip to describe this dependency. Then power usually works out 
fine, since children could be forced to be suspended before parent 
("bus" host).

/BR
/Marcus