On Wed, Oct 09, 2013 at 01:37:56PM -0700, Dylan Reid wrote: > On Sun, Oct 6, 2013 at 8:48 PM, Vinod Koul <vinod.koul@xxxxxxxxx> wrote: > > On Mon, Oct 07, 2013 at 10:39:34AM +0900, Chanho Park wrote: > >> > > Why didn't you use a cookie value to track the request? > >> > > The cookie is assigned when each transfer is submitted. > >> > > If you save the value in the desc, we can find the request easily. > >> > > >> > If there are several cyclic desc in the work list, is there a better way > >> > to find the "current" one? The chan struct tracks the last completed and > >> > last submitted cookies, but these will be the first and last > >> > respectively as long as the cyclic transfer is active. Is there an > >> > "active" cookie stored somewhere that I missed? > >> > >> Assume there are three cookies. If you want to get the second cookie not > >> latest cookie, your way can be also correct in such case? > >> I think tx_status API is to get dma status of the given cookie. > >> You are only considering a cyclic case. > > For cyclic case you would have possible same descriptor running till you > > terminate. > > The cyclic case that makes this interesting is when there are multiple > cyclic descriptors in the list. The cookie and completed_cookie > markers don't help to determine which of the descriptors in the list > is currently active. dma_cookie_complete isn't called for a cyclic > desc, the desc is just pushed to the end of the list. Yes the cyclic is a very different case. I think driver can still return for cyclic case which was txstate->last and that will give clue to client which is getting processed now! > > For non cyclic, if you have 3 descriptors submitted, the cookie value can be, say > > 7, 8 and 9. If you query the status of any descriptor and pass the last optional > > txstate arg then you will know the last cookie completed. so if txstate->last is > > 7, then 7th was completed and 8 should be running and 9 in queue! > > Got it, but the correct desc for cookie 8 will still have to be > searched for, correct? Yes -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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