From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434Ab2GBMvO (ORCPT ); Mon, 2 Jul 2012 08:51:14 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:32368 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793Ab2GBMvN (ORCPT ); Mon, 2 Jul 2012 08:51:13 -0400 X-AuditID: cbfee61b-b7f776d000002f3f-14-4ff1993f3104 From: Marek Szyprowski To: "'Lars-Peter Clausen'" , "'Mark Brown'" Cc: "'Takashi Iwai'" , alsa-devel@alsa-project.org, swarren@nvidia.com, linux-kernel@vger.kernel.org, "'Laxman Dewangan'" , lrg@ti.com References: <1340866886-24432-1-git-send-email-ldewangan@nvidia.com> <4FEC3B70.5030902@metafoo.de> <20120628121816.GB21029@sirena.org.uk> <4FEC4E62.3020101@metafoo.de> In-reply-to: <4FEC4E62.3020101@metafoo.de> Subject: RE: [alsa-devel] [PATCH] ASoC: snd_dmaengine: add common api for pcm_mmap Date: Mon, 02 Jul 2012 14:50:58 +0200 Organization: SPRC Message-id: <02c301cd5851$572fd440$058f7cc0$%szyprowski@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-index: Ac1VKUX/1uLMvWdCRx6O9dE/eWzzgADJwXJw Content-language: pl X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrJLMWRmVeSWpSXmKPExsVy+t9jQV37mR/9Dd4cNLG4vGsOmwOjx+dN cgGMUVw2Kak5mWWpRfp2CVwZk15tZyw4xFPxa+pT5gbG/5xdjJwcEgImEkvXtrJA2GISF+6t Z+ti5OIQEpjOKNGzfyELhDOLSWLbrytgVWwChhJdb7vYQGwRgQSJ7u5HTCBFzAKrGSWent7O CtFxilGiuXUnWBWngJbE8c4nQAkODmGBEIn9X6VAwiwCqhKP2rewg4T5BYQkJs5SAAnzCrhI zP29hRHCFpT4Mfke2F5moCnrdx5ngrDlJTavecsM0iohoC7x6K8uxDlGEl3L7jJDlIhI3G14 zjqBUXgWkkmzkEyahWTSLCQtCxhZVjGKphYkFxQnpeca6RUn5haX5qXrJefnbmIEB/gz6R2M qxosDjEKcDAq8fD+mPHRX4g1say4MvcQowQHs5II76lpQCHelMTKqtSi/Pii0pzU4kOM0hws SuK8TdYX/IUE0hNLUrNTUwtSi2CyTBycUg2MoTOMBc5KcL2tYORKi5tU5D+xvUpK4dr+6Q83 9MzqNTtiPFFtnVnguter8j2EnZ4f6xSNKZ8toBcRky1rfUXmotLJMmsTPrGKDr6AY78a6z+V ak4wK7U6Un8uIVpNbP2f8BJnvfUJe0PV+b179U5GuDycNuHInZ8CznxsN2vSLi9S5Tg0d7ES S3FGoqEWc1FxIgBwZhbKbAIAAA== X-TM-AS-MML: No Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thursday, June 28, 2012 2:30 PM Lars-Peter Clausen wrote: > On 06/28/2012 02:18 PM, Mark Brown wrote: > > On Thu, Jun 28, 2012 at 02:15:38PM +0200, Takashi Iwai wrote: > >> Lars-Peter Clausen wrote: > > > >>> to the ALSA core. Now that there is a generic dma_mmap_writecombine it may > >>> make sense to integrate this with snd_pcm_lib_default_mmap. > > > >> Agreed. > > > >> Also, it must be portable. So far, only ARM has > >> dma_mmap_writecombine(), thus the build on other arch would fail as > >> is. > > > > Oh, dear - this means we don't actually have a generic API at all. Is > > there any effort being made to make this generally available? > > Yes there is, and in fact in next/master there is generic > dma_mmap_writecombine. I'm not quite sure how it behaves on non ARM archs > though. But in theory it should fallback to a normal coherent mapping. Marek > did a lot of work on this, I've put him on Cc. On architectures which don't support DMA_ATTR_WRITECOMBINE attribute it falls back to standard 'coherent' implementation, so it is equivalent to dma_mmap_coherent(). If architecture doesn't provide mmap callback, my patch provides a so called 'generic' implementation based on virt_to_phys() macro. Once this patch gets merged, I hope that each architecture will be reviewed if such implementation is correct. If not, some architectures might need to provide their own implementations, but at least we can get the buffer-mmap related hacks from the device drivers. Best regards -- Marek Szyprowski Samsung Poland R&D Center