From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752853AbYLRR2X (ORCPT ); Thu, 18 Dec 2008 12:28:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751391AbYLRR17 (ORCPT ); Thu, 18 Dec 2008 12:27:59 -0500 Received: from wa-out-1112.google.com ([209.85.146.179]:59359 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751046AbYLRR16 (ORCPT ); Thu, 18 Dec 2008 12:27:58 -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=YAkhtl2gpLIDp1Kmg2MK35iyTtcYTKhLlQ7supx5zUczuQkEd65eswOjENzjjM1DA4 FaixI5AcDg1xgeKUr6qwrSznqa6XP48kegm5K/tVs3xW3vushRo6GyY6rT8c28FeshRN 8Jte9RZGtfjjr498SCW0b9+Pkl2Yy7WANG3jY= Message-ID: Date: Thu, 18 Dec 2008 10:27:56 -0700 From: "Dan Williams" To: "Sosnowski, Maciej" Subject: Re: [PATCH 07/13] dmaengine: introduce dma_request_channel and private channels Cc: "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "hskinnemoen@atmel.com" , "g.liakhovetski@gmx.de" , "nicolas.ferre@atmel.com" In-Reply-To: <129600E5E5FB004392DDC3FB599660D70C984F6A@irsmsx504.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20081114213300.32354.1154.stgit@dwillia2-linux.ch.intel.com> <20081114213453.32354.53002.stgit@dwillia2-linux.ch.intel.com> <129600E5E5FB004392DDC3FB599660D70C8F3406@irsmsx504.ger.corp.intel.com> <129600E5E5FB004392DDC3FB599660D70C984F6A@irsmsx504.ger.corp.intel.com> X-Google-Sender-Auth: fff47676d9f6754a Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 18, 2008 at 7:33 AM, Sosnowski, Maciej wrote: > What about situation, where some or all "public" channels in the system > have been claimed by one client for its exclusive usage > before another client appears trying to use available "public" channels? > Despite of presence in the system of channels that supposed to be "public", > the second cilent realizes that the channels are not available anymore at all > or at least limited... > Doesn't it contradict the general idea of "public" (general purpose) channels? > If a greedy module comes along and grabs all the channels via dma_request_channel() then yes, there will be nothing left for the public pool. So, there is a requirement to "play nice". If this becomes an issue in practice we could add a DMA_NO_PRIVATE flag to reserve a channel for public-only usage. Regards, Dan