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 X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06D5BC04ABB for ; Tue, 11 Sep 2018 07:36:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B47C92086A for ; Tue, 11 Sep 2018 07:36:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hpUFxOU1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B47C92086A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727441AbeIKMei (ORCPT ); Tue, 11 Sep 2018 08:34:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:37572 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726305AbeIKMeh (ORCPT ); Tue, 11 Sep 2018 08:34:37 -0400 Received: from localhost (unknown [171.76.126.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 25A7420865; Tue, 11 Sep 2018 07:36:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1536651397; bh=++P0gGCRlK+L/iV6KM40zTkJGbfilgruck7EGj4bpA4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hpUFxOU16vOYO5Dnggm7BZJnUjNlEqd7WBooy2mOB9CPaiOP1RSd3dlp4ywi+Fwe0 65uxo4dwjKCDsJuyYdUt0a5+glla1yLuSY4EeKxjZmKS73YhJgolyN/FfX73YsT4ki AL2u7RTqiFFPjNnGYJUE8B9WhTJllK/FfseMkDNk= Date: Tue, 11 Sep 2018 13:06:27 +0530 From: Vinod To: Peter Ujfalusi Cc: dan.j.williams@intel.com, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, lars@metafoo.de, radheys@xilinx.com Subject: Re: [PATCH v2 2/2] dmaengine: doc: Add sections for per descriptor metadata support Message-ID: <20180911073627.GL2634@vkoul-mobl> References: <20180830121910.16005-1-peter.ujfalusi@ti.com> <20180830121910.16005-3-peter.ujfalusi@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180830121910.16005-3-peter.ujfalusi@ti.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30-08-18, 15:19, Peter Ujfalusi wrote: > Update the provider and client documentation with details about the > metadata support. It would make sense to make this patch 1 :) > > Signed-off-by: Peter Ujfalusi > --- > Documentation/driver-api/dmaengine/client.rst | 70 +++++++++++++++++++ > .../driver-api/dmaengine/provider.rst | 46 ++++++++++++ > 2 files changed, 116 insertions(+) > > diff --git a/Documentation/driver-api/dmaengine/client.rst b/Documentation/driver-api/dmaengine/client.rst > index fbbb2831f29f..584a39347cfe 100644 > --- a/Documentation/driver-api/dmaengine/client.rst > +++ b/Documentation/driver-api/dmaengine/client.rst > @@ -151,6 +151,76 @@ 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 are > + 4. Read out the metadate from the pointer Lets put a note here that only one method should be used > + > 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..502c59f75302 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 architecure (DMA controller and peripherals) uses metadata typo architecure > +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 implment either implment -- ~Vinod