On 2015/10/14 18:53, Vinod Koul wrote:
On Thu, Oct 08, 2015 at 10:31:18AM +0200, Lars-Peter Clausen wrote:
Basically I agree not to expose dma's quirk to slave controllers...But, the
fact I mentioned on cover letter explain the reasons why I have to let slave
controllers know that they are working with a broken dma. It's a dilemma
that if we don't want that to be exposed(let slave controllers' driver get
the info via a API), we have t add broken quirk for all of them ,here and
there, which seems to be a disaster:(
The problem with this API is that it transports values with device specific
meanings over a generic API. Which is generally speaking not a good idea
because the consumer witch is supposed to be generic suddenly needs to know
which provider it is talking to.
A better solution in this case typically is either introduce a generic API
with generic values or a custom API with custom values, but don't mix the two.
I would appreciate it if you could give me some suggestions at your earliest
convenience. :)
In this case I think the best way to handle this is not quirks, but rather
expose the actual maximum burst size using the DMA capabilities API. Since
supporting only a certain burst depth is not really a quirk. All hardware
has a limit for this and for some it might be larger or smaller than for
others and it might be the same IP core but the maximum size depends on some
IP core parameters. So this should be discoverable.
yes that makes more sense than adding quirks, exposing the right values
which should be a readable property for driver will ensure it works on
system with/without quirks
Sorry for late response in this thread.
Right, we can expose max-burst to clients by dma_slave_caps instead of
quirks. I will try it and send v6 ASAP.
Thanks Lars and Vinod.
--
Best Regards
Shawn Lin
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