From patchwork Mon Nov 11 13:53:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Ujfalusi X-Patchwork-Id: 11237087 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A876014E5 for ; Mon, 11 Nov 2019 13:54:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 64961206A3 for ; Mon, 11 Nov 2019 13:54:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RWxNzKoL"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ti.com header.i=@ti.com header.b="v/6XRVI8" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 64961206A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=ti.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=QzEf7Af4g2J1GMTdWlQnAk2Z5EmrS3CK7cUT4QldjX4=; b=RWxNzKoLqseje0 ZbVUoksDsJj0Y1OT/tgDWUj+Afhqrc/8b1Fy0sNP/FD4ru6P7wZoHEZIICSJc1w3RdCPdmfey5Gyf ZoiECajbsJ5mO0DuZYVOSTo9x4ErADiJwE2zk0lNbx+CeMccx9GiVoqVmRmymhZefHVEfBsbBCGXX /REfXrySNwx19sM5gQ3qnZBVPjTCqbpZJPPRJIcgHJXWzu4ZR7dz+yA37Lfay5yqx3zzgm03wZJf0 kDlhtdeBX1q7g3IyWZy3bDBZ8QJmMKXbkSMUbkhxWQDPmHcbaJfbEWULRwsPpIYxqvR7HsJ21T4gU /kJtMzgi8LGjTbZD5iBA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUA9R-0002Ih-L8; Mon, 11 Nov 2019 13:54:41 +0000 Received: from lelv0142.ext.ti.com ([198.47.23.249]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUA7b-0000iV-I4 for linux-arm-kernel@lists.infradead.org; Mon, 11 Nov 2019 13:52:56 +0000 Received: from fllv0034.itg.ti.com ([10.64.40.246]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id xABDqULr010446; Mon, 11 Nov 2019 07:52:30 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1573480350; bh=uSViP+QvJDzIv6c8dhx5jMKNUxJQ+VwAKiFTRE1e4co=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=v/6XRVI80Ry1WPxwcUMcx9u+u467KI8tzpc+m8yFipmN+ynHn8V1UHqslX9s1AWDs MNsR+F7ZSnboEWtW6Fy5OEB2302/+ajmk96hmHRaJ70LpunEgrkQzw0HjHdUQy8T1E qpI7X9vJrQVFW7RrrLWfdID6vkmCKuDMqgxyTP1E= Received: from DLEE100.ent.ti.com (dlee100.ent.ti.com [157.170.170.30]) by fllv0034.itg.ti.com (8.15.2/8.15.2) with ESMTPS id xABDqU0l111142 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 11 Nov 2019 07:52:30 -0600 Received: from DLEE105.ent.ti.com (157.170.170.35) by DLEE100.ent.ti.com (157.170.170.30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3; Mon, 11 Nov 2019 07:52:12 -0600 Received: from fllv0040.itg.ti.com (10.64.41.20) by DLEE105.ent.ti.com (157.170.170.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3 via Frontend Transport; Mon, 11 Nov 2019 07:52:12 -0600 Received: from feketebors.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id xABDqE8o097668; Mon, 11 Nov 2019 07:52:26 -0600 From: Peter Ujfalusi To: , , , Subject: [PATCH v5 03/15] dmaengine: doc: Add sections for per descriptor metadata support Date: Mon, 11 Nov 2019 15:53:18 +0200 Message-ID: <20191111135330.8235-4-peter.ujfalusi@ti.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191111135330.8235-1-peter.ujfalusi@ti.com> References: <20191111135330.8235-1-peter.ujfalusi@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191111_055247_699457_34D01A6E X-CRM114-Status: GOOD ( 18.20 ) X-Spam-Score: -2.5 (--) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-2.5 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [198.47.23.249 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, grygorii.strashko@ti.com, lokeshvutla@ti.com, j-keerthy@ti.com, linux-kernel@vger.kernel.org, t-kristo@ti.com, tony@atomide.com, dmaengine@vger.kernel.org, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Update the provider and client documentation with details about the metadata support. Signed-off-by: Peter Ujfalusi Reviewed-by: Tero Kristo --- Documentation/driver-api/dmaengine/client.rst | 75 +++++++++++++++++++ .../driver-api/dmaengine/provider.rst | 46 ++++++++++++ 2 files changed, 121 insertions(+) diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst index 45953f171500..41309c176df4 100644 --- a/Documentation/driver-api/dmaengine/client.rst +++ b/Documentation/driver-api/dmaengine/client.rst @@ -151,6 +151,81 @@ The details of these operations are: Note that callbacks will always be invoked from the DMA engines tasklet, never from interrupt context. + Optional: per descriptor metadata + --------------------------------- + DMAengine provides two ways for metadata support. + + DESC_METADATA_CLIENT + + The metadata buffer is allocated/provided by the client driver and it is + attached to the descriptor. + + .. code-block:: c + + int dmaengine_desc_attach_metadata(struct dma_async_tx_descriptor *desc, + void *data, size_t len); + + DESC_METADATA_ENGINE + + The metadata buffer is allocated/managed by the DMA driver. The client + driver can ask for the pointer, maximum size and the currently used size of + the metadata and can directly update or read it. + + .. code-block:: c + + void *dmaengine_desc_get_metadata_ptr(struct dma_async_tx_descriptor *desc, + size_t *payload_len, size_t *max_len); + + int dmaengine_desc_set_metadata_len(struct dma_async_tx_descriptor *desc, + size_t payload_len); + + Client drivers can query if a given mode is supported with: + + .. code-block:: c + + bool dmaengine_is_metadata_mode_supported(struct dma_chan *chan, + enum dma_desc_metadata_mode mode); + + Depending on the used mode client drivers must follow different flow. + + DESC_METADATA_CLIENT + + - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) + construct the metadata in the client's buffer + 2. use dmaengine_desc_attach_metadata() to attach the buffer to the + descriptor + 3. submit the transfer + - DMA_DEV_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) + 2. use dmaengine_desc_attach_metadata() to attach the buffer to the + descriptor + 3. submit the transfer + 4. when the transfer is completed, the metadata should be available in the + attached buffer + + DESC_METADATA_ENGINE + + - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) + 2. use dmaengine_desc_get_metadata_ptr() to get the pointer to the + engine's metadata area + 3. update the metadata at the pointer + 4. use dmaengine_desc_set_metadata_len() to tell the DMA engine the + amount of data the client has placed into the metadata buffer + 5. submit the transfer + - DMA_DEV_TO_MEM: + 1. prepare the descriptor (dmaengine_prep_*) + 2. submit the transfer + 3. on transfer completion, use dmaengine_desc_get_metadata_ptr() to get the + pointer to the engine's metadata area + 4. Read out the metadata from the pointer + + .. note:: + + Mixed use of DESC_METADATA_CLIENT / DESC_METADATA_ENGINE is not allowed, + client drivers must use either of the modes per descriptor. + 4. Submit the transaction Once the descriptor has been prepared and the callback information diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index dfc4486b5743..da557c21c619 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -247,6 +247,52 @@ after each transfer. In case of a ring buffer, they may loop (DMA_CYCLIC). Addresses pointing to a device's register (e.g. a FIFO) are typically fixed. +Per descriptor metadata support +------------------------------- +Some data movement architecture (DMA controller and peripherals) uses metadata +associated with a transaction. The DMA controller role is to transfer the +payload and the metadata alongside. +The metadata itself is not used by the DMA engine itself, but it contains +parameters, keys, vectors, etc for peripheral or from the peripheral. + +The DMAengine framework provides a generic ways to facilitate the metadata for +descriptors. Depending on the architecture the DMA driver can implement either +or both of the methods and it is up to the client driver to choose which one +to use. + +- DESC_METADATA_CLIENT + + The metadata buffer is allocated/provided by the client driver and it is + attached (via the dmaengine_desc_attach_metadata() helper to the descriptor. + + From the DMA driver the following is expected for this mode: + - DMA_MEM_TO_DEV / DEV_MEM_TO_MEM + The data from the provided metadata buffer should be prepared for the DMA + controller to be sent alongside of the payload data. Either by copying to a + hardware descriptor, or highly coupled packet. + - DMA_DEV_TO_MEM + On transfer completion the DMA driver must copy the metadata to the client + provided metadata buffer. + +- DESC_METADATA_ENGINE + + The metadata buffer is allocated/managed by the DMA driver. The client driver + can ask for the pointer, maximum size and the currently used size of the + metadata and can directly update or read it. dmaengine_desc_get_metadata_ptr() + and dmaengine_desc_set_metadata_len() is provided as helper functions. + + From the DMA driver the following is expected for this mode: + - get_metadata_ptr + Should return a pointer for the metadata buffer, the maximum size of the + metadata buffer and the currently used / valid (if any) bytes in the buffer. + - set_metadata_len + It is called by the clients after it have placed the metadata to the buffer + to let the DMA driver know the number of valid bytes provided. + + Note: since the client will ask for the metadata pointer in the completion + callback (in DMA_DEV_TO_MEM case) the DMA driver must ensure that the + descriptor is not freed up prior the callback is called. + Device operations -----------------