From mboxrd@z Thu Jan 1 00:00:00 1970 From: gsantosh@codeaurora.org Subject: Re: customized IOCTL in pcm platform driver. Date: Tue, 9 Oct 2012 01:01:42 -0700 (PDT) Message-ID: References: <4d3d244e3c337274675747eee0404a78.squirrel@www.codeaurora.org> <9c99072a34e9cd171404e40d6e543d13.squirrel@www.codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from wolverine01.qualcomm.com (wolverine01.qualcomm.com [199.106.114.254]) by alsa0.perex.cz (Postfix) with ESMTP id CFC2F26526D for ; Tue, 9 Oct 2012 10:01:43 +0200 (CEST) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Takashi Iwai Cc: alsa-devel@alsa-project.org, lrg@ti.com, gsantosh@codeaurora.org List-Id: alsa-devel@alsa-project.org > At Tue, 9 Oct 2012 00:30:40 -0700 (PDT), > gsantosh@codeaurora.org wrote: >> >> > At Mon, 8 Oct 2012 23:44:40 -0700 (PDT), >> > gsantosh@codeaurora.org wrote: >> >> >> >> > At Mon, 8 Oct 2012 23:30:09 -0700 (PDT), >> >> > gsantosh@codeaurora.org wrote: >> >> >> >> >> >> Hi All, >> >> >> >> >> >> will ALSA framework provide any customized IOCTL functionality in >> PCM >> >> >> platform driver. >> >> > >> >> > No. >> >> > >> >> >> in my system there is a requirement to get some information from >> DSP >> >> to >> >> >> user space and I am thinking to add IOCTL's, is there any method >> to >> >> >> accommodate or how we can address this issue? >> >> > >> >> > You can use hwdep device for any extra methods. >> >> >> >> We need to tie this ioctl with the on going DSP session which will be >> >> difficult When used with hwdep interface. >> > >> > Hm, how can it be difficult? More specific description is needed to >> > answer more. >> >> to communicate with DSP we open up a session and populate that >> information >> in the substream, for this use case during the playback session user >> space >> has to talk to DSP to get some information like time stamp also the time >> stamp statistics, to talk to DSP I need to get hold of the proper >> substream so that the communication with particular session is possible. >> >> I see adding one IOCTL in the platform driver will solve my issue, but >> not >> finding any way to integrate this in the current framework, >> >> if we use the hwdep, not sure how can I get hold of the substream handle >> so I can talk to particular session in DSP. > > A PCM substream can be identified simply by a PCM device number and > a PCM substream index. You can make ioctl to pass these information. > Can you point to any code reference doing this operation? did you mean accessing the sub-stream handle in user space or in the kernel driver. > > Takashi >