From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jose Abreu Subject: Re: [alsa-devel] [PATCH 5/5 v4] ASoC: dwc: Update DOCUMENTATION for I2S Driver Date: Fri, 8 Apr 2016 17:08:32 +0100 Message-ID: <5707D780.4050406@synopsys.com> References: <20160407175326.GX1924@sirena.org.uk> <570782BF.10402@synopsys.com> <5707D3AD.8030308@metafoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5707D3AD.8030308@metafoo.de> Sender: linux-kernel-owner@vger.kernel.org To: Lars-Peter Clausen , Jose Abreu , Mark Brown Cc: alsa-devel@alsa-project.org, lgirdwood@gmail.com, airlied@linux.ie, Vineet.Gupta1@synopsys.com, Alexey.Brodkin@synopsys.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, CARLOS.PALMINHA@synopsys.com, tiwai@suse.com, linux-snps-arc@lists.infradead.org, architt@codeaurora.org List-Id: alsa-devel@alsa-project.org Hi Lars, On 08-04-2016 16:52, Lars-Peter Clausen wrote: > On 04/08/2016 12:06 PM, Jose Abreu wrote: >> Hi Mark, >> >> >> On 07-04-2016 18:53, Mark Brown wrote: >>> On Thu, Apr 07, 2016 at 05:53:59PM +0100, Jose Abreu wrote: >>> >>>> + Optional properties: >>>> + - snps,use-dmaengine: If set the driver will use ALSA DMA engine. If set >>>> + it is required to use the properties 'dmas' and 'dma-names'. >>> This is not a good interface, it's describing Linux internal APIs. If >>> the device needs to operate in PIO mode it should just do that. >> I added this interface because there is no direct way to check if DMA is >> available on the I2S controller so it is not possible to automatically change >> between DMA and PIO mode. As the I2S controller can be built with or without DMA >> support it is necessary to somehow check if DMA is enabled or not and according >> to that use either ALSA DMA engine or the custom platform driver sent in these >> patches. I did not want to remove drivers functionality so I added this property >> to the DT. This way a user can select between DMA and PIO mode. > That's OK, but you need to describe the hardware, not the indented behavior > of the software driver. > Is this okay: "snps,use-dmaengine: Set this boolean paramater if I2S controller has DMA support. If set the properties 'dmas' and 'dma-names' must be also set" ? Best regards, Jose Miguel Abreu