On Fri, 2012-07-06 at 13:36 +0200, Guennadi Liakhovetski wrote:

On Mon, 25 Jun 2012, Arnd Bergmann wrote:

[snip]

quoted

The channel data in the device tree is still in a format
that is specific to that dmaengine driver and interpreted
by it. Using the regular dma_filter_fn prototype is not
necessary, but it would be convenient because the dmaengine
code already knows how to deal with it. If we don't use this
method, how about adding another callback to struct dma_device
like

bool (*device_match)(struct dma_chan *chan, struct property *req);

I like this idea, but why don't we extend it to also cover the non-DT 
case? I.e., why don't we add the above callback (call it "match" or 
"filter" or anything else) to dmaengine operations and inside (the 
extended) dma_request_channel(), instead of calling the filter function, 
passed as a parameter, we loop over all registered DMAC devices and call 
their filter callbacks, 

And I have told you many times, that dmacs should not know anything
about clients. They should be totally agnostic to it.

Clients need to request a specific channel, and that is where changes
should come for. Not having dmac provide one.


-- 
~Vinod