Hi Sylwester,

On Wednesday 14 November 2012 10:23:19 Sylwester Nawrocki wrote:

On 11/13/2012 03:24 PM, Sakari Ailus wrote:

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Hi all,

Comments would be appreciated, either positive or negative. The omap3isp driver does the same check itself currently, but I think this is more generic than that.

Thanks.

On Fri, Oct 26, 2012 at 10:46:17PM +0300, Sakari Ailus wrote:

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If an entity has sink pads, at least one of them must be connected to another pad with an enabled link. If a driver with multiple sink pads has more strict requirements the check should be done in the driver itself.

Just requiring one sink pad is connected with an enabled link is enough API-wise: entities with sink pads with only disabled links should not be allowed to stream in the first place, but also in a different operation mode a device might require only one of its pads connected with an active link.

If an entity has an ability to function as a source entity another logical entity connected to the aforementioned one should be used for the purpose.

Why not leave it to individual drivers ? I'm not sure if it is a good idea not to allow an entity with sink pads to be used as a source only. It might be appropriate for most of the cases but likely not all. I'm inclined not to add this requirement in the API. Just my opinion though.

I have mixed feelings about this patch too, which is why I've asked Sakari to cross-post it. It's pretty easy to add this check to the core now, but pushing it back to drivers late if we realize it's too restrictive would be difficult. I think my preference would go for a helper function that drivers can use, possibly first waiting until a second driver requires this kind of checks before implementing it.