From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars-Peter Clausen Subject: Re: [PATCH 3/6] dma: Add a jz4740 dmaengine driver Date: Fri, 24 May 2013 08:41:05 +0200 Message-ID: <519F0B81.1090009@metafoo.de> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130524055453.GR30200@intel.com> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: alsa-devel@alsa-project.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