From patchwork Mon Jun 6 07:30:12 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shawn Guo X-Patchwork-Id: 1753 Return-Path: Delivered-To: unknown Received: from imap.gmail.com (74.125.159.109) by localhost6.localdomain6 with IMAP4-SSL; 08 Jun 2011 14:55:23 -0000 Delivered-To: patches@linaro.org Received: by 10.52.181.10 with SMTP id ds10cs14841vdc; Mon, 6 Jun 2011 00:21:55 -0700 (PDT) Received: by 10.236.175.7 with SMTP id y7mr5338149yhl.444.1307344914723; Mon, 06 Jun 2011 00:21:54 -0700 (PDT) Received: from mail-pw0-f50.google.com (mail-pw0-f50.google.com [209.85.160.50]) by mx.google.com with ESMTPS id h27si20315123yhe.38.2011.06.06.00.21.54 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 06 Jun 2011 00:21:54 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.160.50 is neither permitted nor denied by best guess record for domain of shawn.guo@linaro.org) client-ip=209.85.160.50; Authentication-Results: mx.google.com; spf=neutral (google.com: 209.85.160.50 is neither permitted nor denied by best guess record for domain of shawn.guo@linaro.org) smtp.mail=shawn.guo@linaro.org Received: by pwi3 with SMTP id 3so2199370pwi.37 for ; Mon, 06 Jun 2011 00:21:53 -0700 (PDT) Received: by 10.68.31.104 with SMTP id z8mr1983138pbh.220.1307344913247; Mon, 06 Jun 2011 00:21:53 -0700 (PDT) Received: from localhost.localdomain ([114.216.154.92]) by mx.google.com with ESMTPS id w2sm3488934pbg.37.2011.06.06.00.21.35 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 06 Jun 2011 00:21:52 -0700 (PDT) From: Shawn Guo To: linux-kernel@vger.kernel.org Cc: vinod.koul@intel.com, dan.j.williams@intel.com, cjb@laptop.org, linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, patches@linaro.org, Shawn Guo Subject: [PATCH v2 1/3] dmaengine: add new dma API for max_segment_number Date: Mon, 6 Jun 2011 15:30:12 +0800 Message-Id: <1307345414-26872-1-git-send-email-shawn.guo@linaro.org> X-Mailer: git-send-email 1.7.4.1 Like dma_set(get)_max_seg_size for max_segment_size, the patch adds max_segment_number into device_dma_parameters and creates the corresponding dmaengine API dma_set(get)_max_seg_number for it. Here is the user story that tells the need of the new api. The mxs-mmc is the mmc host controller for Freescale MXS architecture. There are a pair of mmc host specific parameters max_seg_size and max_segs that mxs-mmc host driver needs to tell mmc core, so that mmc core can know how big each data segment could be and how many segments could be handled one time in a scatter list by host driver. The mxs-mmc driver is one user of dmaengine mxs-dma, and it will call mxs-dma to transfer data in scatter list. That is to say mxs-mmc has no idea of what max_seg_size and max_segs should be, because they are all mxs-dma capability parameters, and mxs-mmc needs to query them from mxs-dma. Right now, there is well defined dma api (dma_get_max_seg_size) for mmc to query max_seg_size from dma driver, but the one for max_segs is missing. That's why mxs-mmc driver has to hard-code it. The mxs-mmc is just one example to demonstrate the need of the new api, and there are other mmc host drivers (mxcmmc on imx-dma is another example) and possibly even other dmaengine users need this new api to know the maximum segments that dma driver can handle per dma call. Signed-off-by: Shawn Guo --- Changes since v1: * Update commit message to explain why the new api is needed include/linux/device.h | 1 + include/linux/dma-mapping.h | 15 +++++++++++++++ 2 files changed, 16 insertions(+), 0 deletions(-) diff --git a/include/linux/device.h b/include/linux/device.h index c66111a..44cb2528 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -487,6 +487,7 @@ struct device_dma_parameters { * sg limitations. */ unsigned int max_segment_size; + unsigned int max_segment_number; unsigned long segment_boundary_mask; }; diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index ba8319a..fd314f4 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -131,6 +131,21 @@ static inline unsigned int dma_set_max_seg_size(struct device *dev, return -EIO; } +static inline unsigned int dma_get_max_seg_number(struct device *dev) +{ + return dev->dma_parms ? dev->dma_parms->max_segment_number : 1; +} + +static inline unsigned int dma_set_max_seg_number(struct device *dev, + unsigned int number) +{ + if (dev->dma_parms) { + dev->dma_parms->max_segment_number = number; + return 0; + } else + return -EIO; +} + static inline unsigned long dma_get_seg_boundary(struct device *dev) { return dev->dma_parms ?