From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3A6ECC433FE for ; Tue, 3 May 2022 20:09:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240795AbiECUMa (ORCPT ); Tue, 3 May 2022 16:12:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242253AbiECUMV (ORCPT ); Tue, 3 May 2022 16:12:21 -0400 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D9AD40938 for ; Tue, 3 May 2022 13:08:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651608508; x=1683144508; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=AbCtiizXn7mtWsj4iItd1wCayDjqPN6a2w8lSyAntQQ=; b=UEZhKjTc+cHeiXLbqLJuDjglv+SxAzMQOaIw7mIQedVc2MGLPjE+nI13 WQEOQcP4QLQI9+1K7THMM9LZX6vq9uIx5C766+wy27uMCNl+HIqy7ckb4 /joWbXzLBEKAJmLxgIAqpNtLmmRD4rhm8isZD+Fmu9KQ+6yDrv4UfTq95 1YY8Syg/xTkPCxr2GkxDbEoP2bHT1Xf32kmGPtU0GL3SQgmBp7tBQzXUM jtcFIC17ORcvuUC4YvmZUGDqECQzfWiyVaBZcBPTtaqQhaNgt7ziKMSvO 8vDINbVMKQMX++NdDM5q1iI9h9GrklGAh4MsZKclcJivplUeEPTDJklq2 A==; X-IronPort-AV: E=McAfee;i="6400,9594,10336"; a="248118258" X-IronPort-AV: E=Sophos;i="5.91,196,1647327600"; d="scan'208";a="248118258" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2022 13:08:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,196,1647327600"; d="scan'208";a="516705376" Received: from bwalker-desk.ch.intel.com ([143.182.136.162]) by orsmga003.jf.intel.com with ESMTP; 03 May 2022 13:08:27 -0700 From: Ben Walker To: vkoul@kernel.org Cc: dmaengine@vger.kernel.org, herbert@gondor.apana.org.au, davem@davemloft.net, mchehab@kernel.org, mporter@kernel.crashing.org, alex.bou9@gmail.com, Ben Walker Subject: [PATCH v2 12/15] dmaengine: Add provider documentation on cookie assignment Date: Tue, 3 May 2022 13:07:25 -0700 Message-Id: <20220503200728.2321188-13-benjamin.walker@intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220503200728.2321188-1-benjamin.walker@intel.com> References: <20220503200728.2321188-1-benjamin.walker@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Clarify the rules on assigning cookies to DMA transactions. Signed-off-by: Ben Walker --- .../driver-api/dmaengine/provider.rst | 45 +++++++++++++++---- 1 file changed, 37 insertions(+), 8 deletions(-) diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index e9e9de18d6b02..7c8ace703c96f 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -421,7 +421,9 @@ supported. - tx_submit: A pointer to a function you have to implement, that is supposed to push the current transaction descriptor to a - pending queue, waiting for issue_pending to be called. + pending queue, waiting for issue_pending to be called. Each + descriptor is given a cookie to identify it. See the section + "Cookie Management" below. - In this structure the function pointer callback_result can be initialized in order for the submitter to be notified that a @@ -526,6 +528,40 @@ supported. - May sleep. +Cookie Management +------------------ + +When a transaction is queued for submission via tx_submit(), the provider +must assign that transaction a cookie (dma_cookie_t) to uniquely identify it. +The provider is allowed to perform this assignment however it wants, but for +convenience the following utility functions are available to create +monotonically increasing cookies + + .. code-block:: c + + void dma_cookie_init(struct dma_chan *chan); + + Called once at channel creation + + .. code-block:: c + + dma_cookie_t dma_cookie_assign(struct dma_async_tx_descriptor *tx); + + Assign a cookie to the given descriptor + + .. code-block:: c + + void dma_cookie_complete(struct dma_async_tx_descriptor *tx); + + Mark the descriptor as complete and invalidate the cookie + + .. code-block:: c + + enum dma_status dma_cookie_status(struct dma_chan *chan, + dma_cookie_t cookie, struct dma_tx_state *state); + + Report the status of the cookie and filling in state, if not NULL. + Misc notes ========== @@ -541,13 +577,6 @@ where to put them) - Makes sure that dependent operations are run before marking it as complete. -dma_cookie_t - -- it's a DMA transaction ID. - -- The value can be chosen by the provider, or use the helper APIs - such as dma_cookie_assign() and dma_cookie_complete(). - DMA_CTRL_ACK - If clear, the descriptor cannot be reused by provider until the -- 2.35.1