Messages in this thread | | | Date | Tue, 30 Aug 2011 09:12:07 +0200 (CEST) | From | Guennadi Liakhovetski <> | Subject | Re: [PATCH] dma: shdma: transfer based runtime PM |
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On Mon, 29 Aug 2011, Vinod Koul wrote:
> On Mon, 2011-08-29 at 14:21 +0200, Guennadi Liakhovetski wrote: > > On Mon, 29 Aug 2011, Vinod Koul wrote: > > > > > On Fri, 2011-08-26 at 01:11 +0200, Guennadi Liakhovetski wrote: > > > > On Thu, 25 Aug 2011, Koul, Vinod wrote: > > > > > Wont it be easy to to do: > > > > > - pm_runtime_get() in each submit > > > > > - pm_runtime_put() in each callback > > > > > Normal case above would work just fine > > > > > - In terminate case, count the number of issued transactions, and call > > > > > pm_runtime_put() for each canceled transaction > > > > > (i am assuming that for each timeout error, the client will call > > > > > terminate) > > > > > > > > As I said, this won't be very easy to do this in a robust way. You'd have > > > > to scan your list of DMA blocks and see, which of them belong to one > > > > descriptor, and once you reach the end of that descriptor, issue a put(). > > > > Perhaps, this can be done, but my choice went to the currently presented > > > > solution. > > > If you count the number of descriptor submitted in your submitted list > > > and call _put for each, I see no reason why it wont be simple and better > > > than current approach. > > > > Sorry, I thought, you wanted to avoid extra counting, because runtime-pm > > counts by itself. Now you propose to count... > see below it doesn't count but iterate thru list
Yes, sorry, iterating is a better word, but I actually meant "counting" in a broad sense, of which "iterating" is a particular case:-)
> > > 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?
Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/
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