Messages in this thread | | | Date | Mon, 5 Sep 2011 10:10:33 +0200 (CEST) | From | Guennadi Liakhovetski <> | Subject | Re: [PATCH] dma: shdma: transfer based runtime PM |
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Hi Vinod
On Tue, 30 Aug 2011, Guennadi Liakhovetski wrote:
> On Tue, 30 Aug 2011, Vinod Koul wrote: > > > On Tue, 2011-08-30 at 09:12 +0200, Guennadi Liakhovetski wrote: > > > On Mon, 29 Aug 2011, Vinod Koul wrote: > > > > > > Something like: > > > > > > /* since callback is set for last descriptor of chain, we call runtime > > > > > > * put for that desc alone > > > > > > */ > > > > > > list_for_each_entry_safe(desc, __desc, sh_chan->ld_queue, node) { > > > > > > if (desc->async_tx.callback) > > > > > > pm_runtime_put(device); > > > > > > > > > > Not all dma users have callbacks. > > > > Do you have such usage today, at least I dont :) > > > > Nevertheless, in tx_submit adding a simple flag in your drivers > > > > descriptor structure can tell you whether to call _put() or not. Agreed? > > > > > > Yes, I agree, that one could make this work too. Still, I do not > > > understand how and why this is better to the extent, that I have to > > > reimplement my patch, retest and resubmit it. Maybe Dan or Paul have an > > > opinion on this? > > But wont it make code look simpler and cleaner, you don't reply on your > > counters but on pm_runtime infrastructure to do the job. > > Sorry, I see it differently. I don't use any counters in my patch. I'm > only checking for empty queue, i.e., I'm just identifying the first > descriptor submission and the last completion or termination. > > > You juts need > > to call _put/_get at right places, which IMO l;ooks lot simpler than > > current approach > > If we didn't have to check for exact symmetry, then yes, I agree, this > would be cleaner. I.e., if we indeed had well-defined entry- and > exit-points, which are guaranteed to be called exact same number of times. > Like, e.g., with file open() / close() etc. But since we don't have this > symmetry, and instead have to add flags and iterate lists, this doesn't > look natural and simple to me anymore, sorry.
What about this one? Would you be prepared to take it as is, or you still think, that a pm_runtime_get*() on each descriptor submission would be better?
Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/
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