From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m56FKtbU030272 for ; Fri, 6 Jun 2008 11:20:55 -0400 Received: from smtp206.iad.emailsrvr.com (smtp206.iad.emailsrvr.com [207.97.245.206]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id m56FKjXL029883 for ; Fri, 6 Jun 2008 11:20:45 -0400 From: Jon Dufresne To: Mauro Carvalho Chehab In-Reply-To: <20080605180748.0b8f81cd@gaivota> References: <1212675977.16563.24.camel@localhost.localdomain> <20080605180748.0b8f81cd@gaivota> Content-Type: text/plain Date: Fri, 06 Jun 2008 10:29:52 -0400 Message-Id: <1212762592.16563.54.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Cc: video4linux-list@redhat.com Subject: Re: Writing first v4l2 driver Reply-To: jon.dufresne@infinitevideocorporation.com List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: video4linux-list-bounces@redhat.com Errors-To: video4linux-list-bounces@redhat.com List-ID: On Thu, 2008-06-05 at 18:07 -0300, Mauro Carvalho Chehab wrote: > Does your device support DMA scatter/gather mode (e.g. instead of a continuous > DMA memory, you would be using a range of non-continuous memory areas)? If not, > then you'll need to write a different video-buf driver. I am writing code for both sides, the DSP on the PCI board and the driver in the linux kernel. The dsp has functionality to write data over the PCI bus, and I could certainly code this to work in discontinuous chunks. So I believe it could use sg lists. > The simplest driver is vivi.c. Yet, it uses videobuf-vmalloc, which is a little > bit different. However, since this is a fake device, it helps to understand how > videobuf works. If you get into vivi.c previous versions, at mercurial repo, > you'll find even a vivi example using the video-buf-dma-sg. Most of stuff > will be similar. > > The other two examples for PCI devices are saa7134-video and cx88-video. bttv > also uses it, but bttv driver is more complex to understand, since its code is > bigger. Thanks for pointing these devices out. I will study these and see how things turn out. Thanks again, Jon -- video4linux-list mailing list Unsubscribe mailto:video4linux-list-request@redhat.com?subject=unsubscribe https://www.redhat.com/mailman/listinfo/video4linux-list