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{
    "id": 816409,
    "url": "http://patchwork.ozlabs.org/api/patches/816409/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/linux-i2c/patch/20170920185956.13874-3-wsa+renesas@sang-engineering.com/",
    "project": {
        "id": 35,
        "url": "http://patchwork.ozlabs.org/api/projects/35/?format=api",
        "name": "Linux I2C development",
        "link_name": "linux-i2c",
        "list_id": "linux-i2c.vger.kernel.org",
        "list_email": "linux-i2c@vger.kernel.org",
        "web_url": "",
        "scm_url": "",
        "webscm_url": "",
        "list_archive_url": "",
        "list_archive_url_format": "",
        "commit_url_format": ""
    },
    "msgid": "<20170920185956.13874-3-wsa+renesas@sang-engineering.com>",
    "list_archive_url": null,
    "date": "2017-09-20T18:59:52",
    "name": "[RFC,v5,2/6] i2c: add helpers to ease DMA handling",
    "commit_ref": null,
    "pull_url": null,
    "state": "superseded",
    "archived": false,
    "hash": "47233e35813774c47fe6addc90dbe459c65d834b",
    "submitter": {
        "id": 69646,
        "url": "http://patchwork.ozlabs.org/api/people/69646/?format=api",
        "name": "Wolfram Sang",
        "email": "wsa+renesas@sang-engineering.com"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/linux-i2c/patch/20170920185956.13874-3-wsa+renesas@sang-engineering.com/mbox/",
    "series": [
        {
            "id": 4199,
            "url": "http://patchwork.ozlabs.org/api/series/4199/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/linux-i2c/list/?series=4199",
            "date": "2017-09-20T18:59:56",
            "name": "i2c: document DMA handling and add helpers for it",
            "version": 5,
            "mbox": "http://patchwork.ozlabs.org/series/4199/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/816409/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/816409/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<linux-i2c-owner@vger.kernel.org>",
        "X-Original-To": "incoming@patchwork.ozlabs.org",
        "Delivered-To": "patchwork-incoming@bilbo.ozlabs.org",
        "Authentication-Results": "ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=linux-i2c-owner@vger.kernel.org;\n\treceiver=<UNKNOWN>)",
        "Received": [
            "from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3xy8Hb0KFdz9sNr\n\tfor <incoming@patchwork.ozlabs.org>;\n\tThu, 21 Sep 2017 05:02:03 +1000 (AEST)",
            "(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1751723AbdITTBp (ORCPT <rfc822;incoming@patchwork.ozlabs.org>);\n\tWed, 20 Sep 2017 15:01:45 -0400",
            "from sauhun.de ([88.99.104.3]:38837 \"EHLO pokefinder.org\"\n\trhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP\n\tid S1751476AbdITTAE (ORCPT <rfc822;linux-i2c@vger.kernel.org>);\n\tWed, 20 Sep 2017 15:00:04 -0400",
            "from localhost (p54B332E6.dip0.t-ipconnect.de [84.179.50.230])\n\tby pokefinder.org (Postfix) with ESMTPSA id 6C2CB2C439B;\n\tWed, 20 Sep 2017 21:00:02 +0200 (CEST)"
        ],
        "From": "Wolfram Sang <wsa+renesas@sang-engineering.com>",
        "To": "linux-i2c@vger.kernel.org",
        "Cc": "linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org,\n\tlinux-iio@vger.kernel.org, linux-input@vger.kernel.org,\n\tlinux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,\n\tWolfram Sang <wsa+renesas@sang-engineering.com>",
        "Subject": "[RFC PATCH v5 2/6] i2c: add helpers to ease DMA handling",
        "Date": "Wed, 20 Sep 2017 20:59:52 +0200",
        "Message-Id": "<20170920185956.13874-3-wsa+renesas@sang-engineering.com>",
        "X-Mailer": "git-send-email 2.11.0",
        "In-Reply-To": "<20170920185956.13874-1-wsa+renesas@sang-engineering.com>",
        "References": "<20170920185956.13874-1-wsa+renesas@sang-engineering.com>",
        "Sender": "linux-i2c-owner@vger.kernel.org",
        "Precedence": "bulk",
        "List-ID": "<linux-i2c.vger.kernel.org>",
        "X-Mailing-List": "linux-i2c@vger.kernel.org"
    },
    "content": "One helper checks if DMA is suitable and optionally creates a bounce\nbuffer, if not. The other function returns the bounce buffer and makes\nsure the data is properly copied back to the message.\n\nSigned-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>\n---\n drivers/i2c/i2c-core-base.c | 45 +++++++++++++++++++++++++++++++++++++++++++++\n include/linux/i2c.h         |  3 +++\n 2 files changed, 48 insertions(+)",
    "diff": "diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c\nindex 56e46581b84bdb..925a22794d3ced 100644\n--- a/drivers/i2c/i2c-core-base.c\n+++ b/drivers/i2c/i2c-core-base.c\n@@ -2241,6 +2241,51 @@ void i2c_put_adapter(struct i2c_adapter *adap)\n }\n EXPORT_SYMBOL(i2c_put_adapter);\n \n+/**\n+ * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg\n+ * @msg: the message to be checked\n+ * @threshold: the amount of byte from which using DMA makes sense\n+ *\n+ * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.\n+ *\n+ *\t   Or a valid pointer to be used with DMA. Note that it can either be\n+ *\t   msg->buf or a bounce buffer. After use, release it by calling\n+ *\t   i2c_release_dma_safe_msg_buf().\n+ *\n+ * This function must only be called from process context!\n+ */\n+u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold)\n+{\n+\tif (msg->len < threshold)\n+\t\treturn NULL;\n+\n+\tif (msg->flags & I2C_M_DMA_SAFE)\n+\t\treturn msg->buf;\n+\n+\tif (msg->flags & I2C_M_RD)\n+\t\treturn kzalloc(msg->len, GFP_KERNEL);\n+\telse\n+\t\treturn kmemdup(msg->buf, msg->len, GFP_KERNEL);\n+}\n+EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf);\n+\n+/**\n+ * i2c_release_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg\n+ * @msg: the message to be synced with\n+ * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.\n+ */\n+void i2c_release_dma_safe_msg_buf(struct i2c_msg *msg, u8 *buf)\n+{\n+\tif (!buf || buf == msg->buf)\n+\t\treturn;\n+\n+\tif (msg->flags & I2C_M_RD)\n+\t\tmemcpy(msg->buf, buf, msg->len);\n+\n+\tkfree(buf);\n+}\n+EXPORT_SYMBOL_GPL(i2c_release_dma_safe_msg_buf);\n+\n MODULE_AUTHOR(\"Simon G. Vogl <simon@tk.uni-linz.ac.at>\");\n MODULE_DESCRIPTION(\"I2C-Bus main module\");\n MODULE_LICENSE(\"GPL\");\ndiff --git a/include/linux/i2c.h b/include/linux/i2c.h\nindex d501d3956f13f0..1e99342f180f45 100644\n--- a/include/linux/i2c.h\n+++ b/include/linux/i2c.h\n@@ -767,6 +767,9 @@ static inline u8 i2c_8bit_addr_from_msg(const struct i2c_msg *msg)\n \treturn (msg->addr << 1) | (msg->flags & I2C_M_RD ? 1 : 0);\n }\n \n+u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold);\n+void i2c_release_dma_safe_msg_buf(struct i2c_msg *msg, u8 *buf);\n+\n int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr);\n /**\n  * module_i2c_driver() - Helper macro for registering a modular I2C driver\n",
    "prefixes": [
        "RFC",
        "v5",
        "2/6"
    ]
}