From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933746AbbENUco (ORCPT ); Thu, 14 May 2015 16:32:44 -0400 Received: from smtp05.smtpout.orange.fr ([80.12.242.127]:45590 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933639AbbENUcl (ORCPT ); Thu, 14 May 2015 16:32:41 -0400 X-ME-Helo: belgarion X-ME-Date: Thu, 14 May 2015 22:32:38 +0200 X-ME-IP: 92.156.128.44 From: Robert Jarzmik To: Maxime Ripard Cc: Vinod Koul , Jonathan Corbet , Daniel Mack , Haojian Zhuang , dmaengine@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3 6/6] Documentation: dmaengine: document DMA_CTRL_ACK References: <1431626006-1708-1-git-send-email-robert.jarzmik@free.fr> <1431626006-1708-6-git-send-email-robert.jarzmik@free.fr> <20150514183853.GN4004@lukather> X-URL: http://belgarath.falguerolles.org/ Date: Thu, 14 May 2015 22:31:39 +0200 In-Reply-To: <20150514183853.GN4004@lukather> (Maxime Ripard's message of "Thu, 14 May 2015 20:38:53 +0200") Message-ID: <87twvekij8.fsf@belgarion.home> User-Agent: Gnus/5.130008 (Ma Gnus v0.8) Emacs/24.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Maxime Ripard writes: > Hi Robert, > >> * DMA_CTRL_ACK >> - - Undocumented feature >> - - No one really has an idea of what it's about, besides being >> - related to reusing the DMA transaction descriptors or having >> - additional transactions added to it in the async-tx API >> - - Useless in the case of the slave API >> + - if set, the TX transfer can be reused after being completed. > > Your sentences should start with an upper-case letter. Ack. >> + - there is a guarantee the TX won't be freed until it is acked >> + by async_tx_ack() > > We never talked about what a "TX transfer" is in the > documentation. That should be documented. I'll remove the "TX", the transfer is widely used in this documentation. > >> + - as a consequence, if a device driver wants to skip the dma_map_sg() and >> + dma_unmap_sg() because the DMA'd data wasn't used, it can resubmit the >> + transfer right after its completion. > > From a provider PoV, the data should always be mapped and / or > allocated in coherent way, so I'm not sure how does that's relevant in > the provider doc. It's relevant because it says the mapping/unmapping is not necessary _between_ 2 submission of a transfer. This implies it is mapped, as it is a requirement for the very first submission. > Also, we should still mention that it's !slave API only. Certainly not, it's fully slave API, that's the purpose of this patch. -- Robert