Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756560AbYLJT6V (ORCPT ); Wed, 10 Dec 2008 14:58:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754752AbYLJT6M (ORCPT ); Wed, 10 Dec 2008 14:58:12 -0500 Received: from wa-out-1112.google.com ([209.85.146.183]:53934 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752794AbYLJT6K (ORCPT ); Wed, 10 Dec 2008 14:58:10 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references:x-google-sender-auth; b=SIDJs24bXI4I0Qf1vMvhZSWsRyNg2jFW7BBX87NYEOWHaO2pBXB8KnMJWuEOIVzXWB OygfBIrJD9XNdGTUOyBnzPlkGm5Ih29euQjb34XhYfemxw2Yp3BdFfHIlCf2x6FEwiRk B7Z4zZNOtU5ImVSz4FqWFKdvqCAgx43JNw8Wk= Message-ID: Date: Wed, 10 Dec 2008 12:58:09 -0700 From: "Dan Williams" To: "Guennadi Liakhovetski" Subject: Re: [PATCH 1/4 v2] dmaengine: add a tx_free method to struct dma_async_tx_descriptor Cc: linux-kernel@vger.kernel.org, linux-fbdev-devel@lists.sourceforge.net, adaplas@gmail.com, "Sascha Hauer" , linux-arm-kernel@lists.arm.linux.org.uk In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: X-Google-Sender-Auth: 560adfdf162ca7e6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1086 Lines: 29 On Wed, Dec 10, 2008 at 3:36 AM, Guennadi Liakhovetski wrote: > From: Guennadi Liakhovetski > > Some users reuse DMA transaction descriptors multiple times and need an > explicit call to release them. An example of such a user is Video4Linux, which > has to be able to release descriptors on ioctl(VIDIOC_DQBUF). > > Signed-off-by: Guennadi Liakhovetski Hi Guennadi, Other dmaengine drivers have tasklets that scan the list of completed descriptors and free the "acked" ones. This happens in the cleanup tasklet... /me looks ...hmm this driver does not have a cleanup routine? Ideally support for ioctl(VIDIOC_DQBUF) could be achieved through this mechanism without needing to increase the size of dma_async_tx_descriptor (which has cache utilization impacts on other drivers). -- Dan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/