Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759595AbcDESJ2 (ORCPT ); Tue, 5 Apr 2016 14:09:28 -0400 Received: from mga14.intel.com ([192.55.52.115]:28556 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933578AbcDESJU (ORCPT ); Tue, 5 Apr 2016 14:09:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,444,1455004800"; d="scan'208";a="681272443" Date: Tue, 5 Apr 2016 11:08:05 -0700 From: Vinod Koul To: Shawn Lin Cc: Doug Anderson , Mark Brown , linux-spi@vger.kernel.org, "linux-kernel@vger.kernel.org" , Dan Carpenter , "open list:ARM/Rockchip SoC..." Subject: Re: [PATCH 3/3] spi: rockchip: check requesting dma channel with EPROBE_DEFER Message-ID: <20160405180804.GB8930@vkoul-mobl.iind.intel.com> References: <1457511043-2058-1-git-send-email-shawn.lin@rock-chips.com> <1457511092-2216-1-git-send-email-shawn.lin@rock-chips.com> <56F0A7F0.5000900@rock-chips.com> <56F0B3A1.9080509@rock-chips.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56F0B3A1.9080509@rock-chips.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 976 Lines: 26 On Tue, Mar 22, 2016 at 10:53:21AM +0800, Shawn Lin wrote: > >Strange, but on 4.4 there was some extra code in > >dma_request_slave_channel() that wasn't in > >dma_request_slave_channel_reason(). ...but looks like that all got > >cleaned up in the same CL that added the new name. > > dma_request_chan already return ERR_PTR(-EPROBE_DEFER), but > dma_request_slave_channel ignore this and rewrite it to be NULL. > Strange behaviour looks to me. commit 0ad7c00057dc ("dma: add channel > request API that supports deferred probe") did the right thing, but > what happened then? It was drop for some reasons? > > Hello Vinod, > > Could you please elaborate some more infomation to commit 0ad7c00057dc > ("dma: add channel request API that supports deferred probe") :) ? The request API was cleaned up here and please see the Documentation on how to do this. See the commit a8135d0d7 - dmaengine: core: Introduce new, universal API to request a channel Thanks -- ~Vinod