Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932229AbbKMB0F (ORCPT ); Thu, 12 Nov 2015 20:26:05 -0500 Received: from mail-yk0-f195.google.com ([209.85.160.195]:33200 "EHLO mail-yk0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753877AbbKMB0C (ORCPT ); Thu, 12 Nov 2015 20:26:02 -0500 MIME-Version: 1.0 In-Reply-To: <564538B4.20402@hurleysoftware.com> References: <1447338836-8785-1-git-send-email-matwey@sai.msu.ru> <1447338836-8785-3-git-send-email-matwey@sai.msu.ru> <20151112195707.5e9cb1d8@lxorguk.ukuu.org.uk> <5644F4F2.2080408@hurleysoftware.com> <564538B4.20402@hurleysoftware.com> Date: Fri, 13 Nov 2015 03:26:01 +0200 Message-ID: Subject: Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag for struct serial_rs485 From: Andy Shevchenko To: Peter Hurley Cc: One Thousand Gnomes , "Matwey V. Kornilov" , Greg Kroah-Hartman , jslaby@suse.com, "linux-kernel@vger.kernel.org" , "linux-serial@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1449 Lines: 32 On Fri, Nov 13, 2015 at 3:11 AM, Peter Hurley wrote: > On 11/12/2015 07:41 PM, Andy Shevchenko wrote: >> On Thu, Nov 12, 2015 at 10:22 PM, Peter Hurley wrote: >>> On 11/12/2015 02:57 PM, One Thousand Gnomes wrote: >> >>> An illustrative (kernel-space) example is the mess that is dmaengine_pause(). >>> Some DMA implementations provide the means to stop and restart DMA without >>> losing data and some DMA implementations do not. Unfortunately, some >>> advertise they support dmaengine_pause() but only for lossy uses like audio. >>> Because the api hides this, the query interface for pause support is >>> useless. >> >> The DMA pause() call means only pause with possibility to resume. >> There is a resume() call as well. Any driver which treats pause() as a >> complete stop is buggy driver and should be fixed. > > How about pause _without_ the possibility to resume? > > https://groups.google.com/d/msg/linux.kernel/Abe0hfGcgsw/H0se55wC558J Briefly what I got from the thread that Russel shows similar view on the API, so that's why he was objecting to add pause/resume calls for a specific hardware. -- With Best Regards, Andy Shevchenko -- 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/