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 EE4E1C43334 for ; Wed, 22 Jun 2022 18:54:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376927AbiFVSyp (ORCPT ); Wed, 22 Jun 2022 14:54:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377736AbiFVSyQ (ORCPT ); Wed, 22 Jun 2022 14:54:16 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B64AF4092B; Wed, 22 Jun 2022 11:54:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655924047; x=1687460047; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=0WsFvoGYgiGnVS8P+Hg1gGwngMRIqqhXjP5myyi7RDo=; b=E/QhVCtSiWRwksrumdYUvUMkMlxAjWtSEKVVVjipaAgyfojmLmkCvWP6 emOxNCb3NL9FB/yER9Z6Mezb+GCk5Cpd8k0PABV0f45FNJ86aaeTHXLwU hiIHVAWnUErud89fLa7lLZ2D9AL1s3tujhOPnfiagiKjqz3JGVU3uACGR mR2fselybitnr0CofY4iF94lKIkam1kUATuLYB688GqRWNg7Mp6R2F53l fSsfBU7erlGqzhJtWkc5SJWU8txfL9zdhZ7FtgODcqQgEoJpqcsNGJMtO oTGUmGAY6UNOjhjvO/nwDyP89/TprUr28GA9daeO/hDtXdhuAQyy89hmP A==; X-IronPort-AV: E=McAfee;i="6400,9594,10386"; a="305971702" X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="305971702" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 11:54:07 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="730495502" Received: from bwalker-desk.ch.intel.com ([143.182.136.162]) by fmsmga001.fm.intel.com with ESMTP; 22 Jun 2022 11:54:06 -0700 From: Ben Walker To: vkoul@kernel.org Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 12/15] dmaengine: Add provider documentation on cookie assignment Date: Wed, 22 Jun 2022 11:54:02 -0700 Message-Id: <20220622185402.3043630-1-benjamin.walker@intel.com> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 610309276bc9c..db019ec492b58 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -427,7 +427,9 @@ 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 @@ -532,6 +534,40 @@ 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 ========== @@ -547,13 +583,6 @@ 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