From mboxrd@z Thu Jan 1 00:00:00 1970 From: Markus Pargmann Subject: Re: [PATCH v2 05/11] ASoC: fsl-ssi: Add support for imx-pcm-fiq Date: Sun, 14 Apr 2013 17:20:16 +0200 Message-ID: <20130414152016.GE27394@pengutronix.de> References: <1365362721-3731-1-git-send-email-mpa@pengutronix.de> <1365362721-3731-6-git-send-email-mpa@pengutronix.de> <51620CEA.3010703@tabi.org> <20130414103819.GA27394@pengutronix.de> <516AB111.3000007@tabi.org> <20130414141015.GC27394@pengutronix.de> <516AC305.2000800@tabi.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <516AC305.2000800-N01EOCouUvQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Timur Tabi Cc: Fabio Estevam , alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, Mark Brown , Liam Girdwood , Sascha Hauer , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Sun, Apr 14, 2013 at 09:53:57AM -0500, Timur Tabi wrote: > Markus Pargmann wrote: > >In general, imx27 does support SSI with DMA, for example > >MACH_IMX27_VISSTRIM_M10 does use SSI with DMA. But there are special > >boards like Eukrea TLV320 and phycore-ac97 that have to use FIQ instead. > >All of them have a imx27 chip. > > Why is the decision to use FIQ board-specific? All of the hardware > is inside the SoC itself. How could a board make using DMA > impossible? I only ported the imx-ssi ac97 driver code and tested twice using DMA without success. But there is a good description of the problem in imx-ssi: " The WM9712 with which this driver was developed with always sends GPIO status data in slot 12 which we receive in our (PCM-) data stream. The only chance we have is to manually skip this data in the FIQ handler." Regards, Markus -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |