From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars-Peter Clausen Subject: Re: [alsa-devel] [PATCH 14/18] ASoC: davinci: Add edma dmaengine platform driver Date: Thu, 13 Mar 2014 11:28:05 +0100 Message-ID: <53218835.3080909@metafoo.de> References: <1394702320-21743-1-git-send-email-peter.ujfalusi@ti.com> <1394702320-21743-15-git-send-email-peter.ujfalusi@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1394702320-21743-15-git-send-email-peter.ujfalusi@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Peter Ujfalusi Cc: linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org, davinci-linux-open-source@linux.davincidsp.com, joelf@ti.com, nsekhar@ti.com, Liam Girdwood , Jyri Sarha , Tony Lindgren , Mark Brown , mporter@linaro.org, dan.j.williams@intel.com, vinod.koul@intel.com List-Id: linux-omap@vger.kernel.org On 03/13/2014 10:18 AM, Peter Ujfalusi wrote: [...] > +static const struct snd_pcm_hardware edma_pcm_hardware = { > + .info = SNDRV_PCM_INFO_MMAP | > + SNDRV_PCM_INFO_MMAP_VALID | > + SNDRV_PCM_INFO_BATCH | > + SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME | > + SNDRV_PCM_INFO_INTERLEAVED, > + .buffer_bytes_max = 128 * 1024, > + .period_bytes_min = 32, > + .period_bytes_max = 64 * 1024, > + .periods_min = 2, > + .periods_max = 19, /* Limit by edma dmaengine driver */ > +}; The idea is that we can auto-discover all the things using the dma_slave_caps API. Too bad we removed the possibility to specify the maximum number of segments from the API. Maybe we need to add it back. Is the 19 a hard-limit or could it be worked around by software in the dmaengine driver? > + > +static const struct snd_dmaengine_pcm_config edma_dmaengine_pcm_config = { > + .pcm_hardware = &edma_pcm_hardware, > + .prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config, > + .prealloc_buffer_size = 128 * 1024, Unless there is a very good reason for exactly this size, just leave it 0 and let the generic dmaengine driver use the default. > +}; > + > +static const struct snd_dmaengine_pcm_config edma_compat_dmaengine_pcm_config = { > + .pcm_hardware = &edma_pcm_hardware, > + .prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config, > + .compat_filter_fn = edma_filter_fn, > + .prealloc_buffer_size = 128 * 1024, > +}; There is no need for different configs for DT and non-DT. > + > +int edma_pcm_platform_register(struct device *dev) > +{ > + if (dev->of_node) > + return snd_dmaengine_pcm_register(dev, > + &edma_dmaengine_pcm_config, > + SND_DMAENGINE_PCM_FLAG_NO_RESIDUE); Since the edma dmaengine driver implements the slave cap API there is no need to manually specify SND_DMAENGINE_PCM_FLAG_NO_RESIDUE manually. But since the edma driver sets the granularity to DMA_RESIDUE_GRANULARITY_DESCRIPTOR in this case the generic dmaengine will not set SND_DMAENGINE_PCM_FLAG_NO_RESIDUE automatically since it assumes that the dmaengine driver is capable of properly reporting the DMA position. > + else > + return snd_dmaengine_pcm_register(dev, > + &edma_compat_dmaengine_pcm_config, > + SND_DMAENGINE_PCM_FLAG_NO_RESIDUE | > + SND_DMAENGINE_PCM_FLAG_NO_DT | > + SND_DMAENGINE_PCM_FLAG_COMPAT); If you set the flags to just SND_DMAENGINE_PCM_FLAG_COMPAT it will do the right thing in the generic dmaengine driver depending on whether dev->of_node is set or not. There is also a devm_ version of snd_dmaengine_pcm_register() it probably makes sense to use it here.