Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034147AbdD0NVx (ORCPT ); Thu, 27 Apr 2017 09:21:53 -0400 Received: from smtprelay.synopsys.com ([198.182.47.9]:54588 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934088AbdD0NVp (ORCPT ); Thu, 27 Apr 2017 09:21:45 -0400 From: Eugeniy Paltsev To: "andriy.shevchenko@linux.intel.com" CC: "vinod.koul@intel.com" , "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , "Alexey.Brodkin@synopsys.com" , "devicetree@vger.kernel.org" , "Eugeniy.Paltsev@synopsys.com" , "linux-snps-arc@lists.infradead.org" , "dan.j.williams@intel.com" , "dmaengine@vger.kernel.org" Subject: Re: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Thread-Topic: [PATCH v2 2/2] dmaengine: Add DW AXI DMAC driver Thread-Index: AQHSr6fifaPEtWYJzkyOcLiQLbUIqKHK/piAgATX+YCAAAwigIAEwr2AgAAREQCAAXZjgIAAMTuAgAFd34CAAXWUAA== Date: Thu, 27 Apr 2017 13:21:41 +0000 Message-ID: <1493299300.25985.17.camel@synopsys.com> References: <1491573855-1039-1-git-send-email-Eugeniy.Paltsev@synopsys.com> <1491573855-1039-3-git-send-email-Eugeniy.Paltsev@synopsys.com> <1492518695.24567.56.camel@linux.intel.com> <1492784977.16657.6.camel@synopsys.com> <1492787583.24567.120.camel@linux.intel.com> <1493049305.25985.4.camel@synopsys.com> <1493052970.24567.168.camel@linux.intel.com> <1493133369.25985.10.camel@synopsys.com> <1493143941.24567.196.camel@linux.intel.com> <1493219075.24567.211.camel@linux.intel.com> In-Reply-To: <1493219075.24567.211.camel@linux.intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.121.8.113] Content-Type: text/plain; charset="utf-8" Content-ID: MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id v3RDLxPM014146 Content-Length: 2233 Lines: 62 On Wed, 2017-04-26 at 18:04 +0300, Andy Shevchenko wrote: > On Tue, 2017-04-25 at 21:12 +0300, Andy Shevchenko wrote: > > On Tue, 2017-04-25 at 15:16 +0000, Eugeniy Paltsev wrote: > > > On Mon, 2017-04-24 at 19:56 +0300, Andy Shevchenko wrote: > > > > On Mon, 2017-04-24 at 15:55 +0000, Eugeniy Paltsev wrote: > > > > Descriptor is active until terminate_all() is called or new > > > > descriptor > > > > is supplied. So, the caller has a quite time to check on it. > > > > > > > > So, what's wrong on it by your opinion? > > > > > > Hmm, this looks OK. (In my example (hsu/hsu.c driver) error > > > descriptors > > > are not freed even after terminate_all is called) > > > > If it's active it will be freed. > > Otherwise caller should check somewhere that descriptor fails. > > > > But actually this is fragile and we need to monitor failed > > descriptors. > > Thanks for reporting. > > > > > > > > > Of course, if you want to keep by some reason (should be stated > > > > what > > > > the reason in comment) erred descriptors, you can do that. > > > > > > So, I'll create desc_error list and store failed descriptors in > > > this > > > list until terminate_all() is called. > > > Is it OK implementation? > > > > Nope, we need to amend virt-chan API for that. I'm on it. Will send > > a series soon. > > I have to correct what I wrote before. > > We have two options: > a) one I proposed above; > b) move descriptor to complete list and call complete callback with > result. > > So, it looks like the b) variant is what is done already in 4 (did I > calculate correctly?) drivers and respective users. In my opinion we should call error descriptor complete callback. But I don't think we should move error descriptor to desc_completed list. When descriptor following our error descriptor will be completed successfully vchan tasklet will be called. So all descriptors from desc_completed list will be freed (including our error descriptor) We'll lost information about error descriptors and we'll not be able to return correct status from dma_async_is_tx_complete(). In my opinion, we should create desc_error list. When we get error we'll move descriptor to desc_error list and call complete callback. --  Eugeniy Paltsev