From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754002Ab2F1OKt (ORCPT ); Thu, 28 Jun 2012 10:10:49 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41845 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751254Ab2F1OKr (ORCPT ); Thu, 28 Jun 2012 10:10:47 -0400 Date: Thu, 28 Jun 2012 16:10:45 +0200 Message-ID: From: Takashi Iwai To: Laxman Dewangan Cc: Mark Brown , Lars-Peter Clausen , "alsa-devel@alsa-project.org" , Stephen Warren , "linux-kernel@vger.kernel.org" , "lrg@ti.com" , Marek Szyprowski Subject: Re: [alsa-devel] [PATCH] ASoC: snd_dmaengine: add common api for pcm_mmap In-Reply-To: <4FEC6399.5050505@nvidia.com> References: <1340866886-24432-1-git-send-email-ldewangan@nvidia.com> <4FEC3B70.5030902@metafoo.de> <20120628121816.GB21029@sirena.org.uk> <4FEC4E62.3020101@metafoo.de> <20120628122830.GJ28922@opensource.wolfsonmicro.com> <4FEC4FA9.20004@nvidia.com> <4FEC5642.9080908@nvidia.com> <4FEC5DC7.5060600@nvidia.com> <4FEC6399.5050505@nvidia.com> User-Agent: Wanderlust/2.15.6 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.7 Emacs/23.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org At Thu, 28 Jun 2012 19:30:57 +0530, Laxman Dewangan wrote: > > On Thursday 28 June 2012 07:21 PM, Takashi Iwai wrote: > > At Thu, 28 Jun 2012 19:06:07 +0530, > > Laxman Dewangan wrote: > > > >>>> Then how about this? > >>>> create new file and header for snd-pcm-writecombine-buffer.c/.h and put > >>>> this in sound/core. > >>>> Select this file compilation through config SND_PCM_WRITECOMBINE_BUFFER > >>>> which will be select this config through sound/soc/xxx/Kconfig if they > >>>> want to use. > >>>> This will provide three apis: new, free and mmap. > >>> Way too much hustles than necessary... > >> Ooh no. :-( I had taken the idea from snd_dmaengine_pcm driver. > >> Bit I like to hear simple way which solves the purpose. > > As Lars suggested, a simple ifdef should suffice for now. > > With the upcoming generic dma_mmap_writecombine() stuff, it'd be even > > simpler in future. > > > > But, still we need to be careful about this. As mentioned, there is > > no flag to know the possibility of writecombine mmap beforehand. > > It'd be nice if we have either a compile-time or a run-time flag / > > function to check that. Then the driver can also expose the mmap > > capability to user-space depending on the flag. > > Yaah, this seems really simple. Thanks for suggestion. > If I understand it fully, the new apis will be declare in sound/pcm.h, > implement it in pcm_native.c and use the config variable > CONFIG_SND_PCM_WRITECOMBINE_BUFFER for ifdef. Or this could be simply ifdef CONFIG_ARM. Since this ifdef will be unnecessary soon later, I don't think we need to give yet another kconfig. Of course, we should put a good comment around there for not keeping it for long time. Takashi