From patchwork Mon Aug 29 20:35:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Walker X-Patchwork-Id: 12958397 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 E4FB8ECAAD4 for ; Mon, 29 Aug 2022 20:36:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229943AbiH2UgN (ORCPT ); Mon, 29 Aug 2022 16:36:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229847AbiH2UgL (ORCPT ); Mon, 29 Aug 2022 16:36:11 -0400 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69CC886C15; Mon, 29 Aug 2022 13:36:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661805370; x=1693341370; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=zm0cSjM3YIXr3tYin2nPtyem0FnSC/v3TJOFRW6jOaI=; b=Ffp4EfiqGyEcZ/qJzvCMj2ryViOuQ70VTxjGa92oMGTtns5qM8zWvWk4 gPYqJsxmnFfZnHMhVn/4dGAY8fV+d60+0UoIWYxvJdY9Zfp4cwbDDSU7W FX+P0c+Wt6CdlQWU8qWBbWoW2HYCGxec7QXp6AiuU2Y34/q0BHpIe6jWg mVR3+LRPrcy+09cncAPUAzr74oGkrTlOrZtU5TuJvhnpUB8HtwCmwuWf1 SzgtPqzH6xJKC+9hn4TIKj4HpA8RMcEYuVEmNdeeXjAxPiAFv/CoA5+jZ fte5d/VP0LjIbwfaD4twuQQDjrUw+6goiR5v2J/p7pIXpHgjjq0LuU8hz Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10454"; a="358958428" X-IronPort-AV: E=Sophos;i="5.93,273,1654585200"; d="scan'208";a="358958428" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Aug 2022 13:36:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,273,1654585200"; d="scan'208";a="614344333" Received: from bwalker-desk.ch.intel.com ([143.182.136.162]) by fmsmga007.fm.intel.com with ESMTP; 29 Aug 2022 13:36:09 -0700 From: Ben Walker To: vkoul@kernel.org Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 4/7] dmaengine: Add provider documentation on cookie assignment Date: Mon, 29 Aug 2022 13:35:34 -0700 Message-Id: <20220829203537.30676-5-benjamin.walker@intel.com> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220829203537.30676-1-benjamin.walker@intel.com> References: <20220622193753.3044206-1-benjamin.walker@intel.com> <20220829203537.30676-1-benjamin.walker@intel.com> MIME-Version: 1.0 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 1d0da2777921d..a5539f816d125 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -417,7 +417,9 @@ 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 @@ -522,6 +524,40 @@ 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 ========== @@ -537,13 +573,6 @@ 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