From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755843Ab3EXGib (ORCPT ); Fri, 24 May 2013 02:38:31 -0400 Received: from mailhost.informatik.uni-hamburg.de ([134.100.9.70]:59762 "EHLO mailhost.informatik.uni-hamburg.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754070Ab3EXGia (ORCPT ); Fri, 24 May 2013 02:38:30 -0400 Message-ID: <519F0B81.1090009@metafoo.de> Date: Fri, 24 May 2013 08:41:05 +0200 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130116 Icedove/10.0.12 MIME-Version: 1.0 To: Vinod Koul CC: Ralf Baechle , Liam Girdwood , Mark Brown , Maarten ter Huurne , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org Subject: Re: [PATCH 3/6] dma: Add a jz4740 dmaengine driver References: <1369341387-19147-1-git-send-email-lars@metafoo.de> <1369341387-19147-4-git-send-email-lars@metafoo.de> <20130524045935.GM30200@intel.com> <519F016C.4040901@metafoo.de> <20130524055453.GR30200@intel.com> In-Reply-To: <20130524055453.GR30200@intel.com> X-Enigmail-Version: 1.4.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/24/2013 07:54 AM, Vinod Koul wrote: > On Fri, May 24, 2013 at 07:58:04AM +0200, Lars-Peter Clausen wrote: >> This one needs both. >> >>>> + jzcfg.mode = JZ4740_DMA_MODE_SINGLE; >>>> + jzcfg.request_type = config->slave_id; >>>> + >>>> + chan->config = *config; >>>> + >>>> + jz4740_dma_configure(chan->jz_chan, &jzcfg); >>>> + >>>> + return 0; >>> You are NOT use src_addr/dstn_addr? How else are you passing the periphral >>> address? >> I'm saving the whole config, which will later be used to retrieve the source or >> dest address. > well I missed that and it is a bad idea. You dont know when client has > freed/thrown the pointer so copy this instead.. I do copy the full config, not just the pointer to the config. Although src_addr and dest_addr are the only two fields which are used later on at this point. So I could change it to just copy src_addr and dest_addr, or well just one of them depending on the direction. > >> >>>> +} >> [...] >>>> +static int jz4740_dma_alloc_chan_resources(struct dma_chan *c) >>>> +{ >>>> + struct jz4740_dmaengine_chan *chan = to_jz4740_dma_chan(c); >>>> + >>>> + chan->jz_chan = jz4740_dma_request(chan, NULL); >>>> + if (!chan->jz_chan) >>>> + return -EBUSY; >>>> + >>>> + jz4740_dma_set_complete_cb(chan->jz_chan, jz4740_dma_complete_cb); >>>> + >>>> + return 0; >>> Zero is not expected value, you need to return the descriptors allocated >>> sucessfully. >> >> Well, zero descriptors have been allocated. As far as I can see only a negative >> return value is treated as an error. Also the core doesn't seem to use the >> return value for anything else but checking if it is an error. > This is the API defination > * @device_alloc_chan_resources: allocate resources and return the > * number of allocated descriptors > But 0 is still the number of descriptors that have been pre-allocated. - Lars