From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755318AbbAFMrG (ORCPT ); Tue, 6 Jan 2015 07:47:06 -0500 Received: from unicorn.mansr.com ([81.2.72.234]:43922 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755054AbbAFMrE convert rfc822-to-8bit (ORCPT ); Tue, 6 Jan 2015 07:47:04 -0500 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Lars-Peter Clausen Cc: Arnd Bergmann , linux-kernel@vger.kernel.org, Ralf Baechle , dmaengine@vger.kernel.org, alsa-devel@alsa-project.org, linux-mmc@vger.kernel.org, linux-mips@linux-mips.org Subject: Re: [PATCH, RFC] MIPS: jz4740: use dma filter function References: <22569458.nE7JkNNnz3@wuerfel> <54ABBCE6.8060904@metafoo.de> Date: Tue, 06 Jan 2015 12:47:00 +0000 In-Reply-To: <54ABBCE6.8060904@metafoo.de> (Lars-Peter Clausen's message of "Tue, 06 Jan 2015 11:45:58 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Lars-Peter Clausen writes: > On 01/05/2015 11:39 PM, Arnd Bergmann wrote: >> As discussed on the topic of shmobile DMA today, jz4740 is the only >> user of the slave_id field in dma_slave_config besides shmobile. This >> use is really incompatible with the way that other drivers use the >> dmaengine API, so we should get rid of it. > > Do you have a link to that discussion? > >> >> This adds a trivial filter function that uses the filter param to >> pass the dma type, and uses that in both drivers. > > In my opinion that's just from bad to worse. Using filter functions > isn't that great in the first place. And using them to pass data from > the consumer to the DMA provider is just a horrible abuse of the API. It seems to me the only sane way to use the dmaengine API is in conjunction with DT. -- Måns Rullgård mans@mansr.com