From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752172AbbBKLCV (ORCPT ); Wed, 11 Feb 2015 06:02:21 -0500 Received: from mailout3.w1.samsung.com ([210.118.77.13]:15454 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751752AbbBKLCT (ORCPT ); Wed, 11 Feb 2015 06:02:19 -0500 X-AuditID: cbfec7f5-b7fc86d0000066b7-7e-54db3625237f Message-id: <54DB36B6.2010409@samsung.com> Date: Wed, 11 Feb 2015 12:02:14 +0100 From: Robert Baldyga User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-version: 1.0 To: Vinod Koul Cc: dan.j.williams@intel.com, lars@metafoo.de, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, m.szyprowski@samsung.com, k.kozlowski@samsung.com, kyungmin.park@samsung.com, l.czerwinski@samsung.com, padma.kvr@gmail.com Subject: Re: [PATCH v3 2/2] dma: pl330: add DMA_PAUSE feature References: <1418208918-28127-1-git-send-email-r.baldyga@samsung.com> <1418208918-28127-3-git-send-email-r.baldyga@samsung.com> <20150211002405.GC21387@intel.com> In-reply-to: <20150211002405.GC21387@intel.com> Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrNLMWRmVeSWpSXmKPExsVy+t/xy7qqZrdDDE5dl7eYPvUCo8XqqX9Z LV6/MLQ42/SG3eLXtElsFksmz2e1uLxrDpvF2iN32S3al81htXjZt5/Fgctj56y77B6L97xk 8ljy5hCrR9+WVYwenzfJBbBGcdmkpOZklqUW6dslcGVcWnyOvaCTs+Jy8z/GBsbV7F2MnBwS AiYSPx6fY4KwxSQu3FvP1sXIxSEksJRRYu6mJcwQzkdGiQN/VoNV8QpoSex/uYMRxGYRUJW4 2tHBBmKzCehIbPk+ASwuKhAhMf/Ya2aIekGJH5PvsYDYIkD1W352MIIMZRZ4ySjx7fI7oGYO DmEBW4k5b6sgli1jlFg/7RjYUE4BfYmFrRvAapgF9CTuX9QCCTMLyEtsXvOWeQKjwCwkK2Yh VM1CUrWAkXkVo2hqaXJBcVJ6rpFecWJucWleul5yfu4mRkgEfN3BuPSY1SFGAQ5GJR5ei5hb IUKsiWXFlbmHGCU4mJVEeCPEbocI8aYkVlalFuXHF5XmpBYfYmTi4JRqYGQvadgUdOnRvfOr /rbedj4SfHy/YRm34Mr0q3zJmzgvprNNenL/ryuDl0mvRlzjT68rMyda55kpBb1Ktdx+iP0s 1yHJ/rwNykKpQk9evXbw+3Sj8rvQnZCr7QdTOQ4kW91sS3f/w7/U8sMUmXOzbxy+m1R9p1ds +ZOXhs+NN6yt/MWikC8ux63EUpyRaKjFXFScCAAWytPdXgIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/11/2015 01:24 AM, Vinod Koul wrote: > On Wed, Dec 10, 2014 at 11:55:18AM +0100, Robert Baldyga wrote: >> DMA_PAUSE command is used for halting DMA transfer on chosen channel. >> It can be useful when we want to safely read residue before terminating >> all requests on channel. Otherwise there can be situation when some data >> is transferred before channel termination but after reading residue, >> which obviously results with data loss. To avoid this situation we can >> pause channel, read residue and then terminate all requests. >> This scenario is common, for example, in serial port drivers. > And where is the resume here? Also this needs rebase > We can't have resume on this hardware. It's in comment. DMA_PAUSE feature is added only to freeze channel state before its termination to allow safe residue read. BTW I was almost sure that you have applied these patches to your tree about two months ago. In mainline kernel there is already samsung serial driver using DMA, which wouldn't work without these changes. Hence it would be great to have my patches applied ASAP. I will send v4 today. Thanks, Robert Baldyga