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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 BBB7CC433DF for ; Mon, 12 Oct 2020 06:09:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89952207BB for ; Mon, 12 Oct 2020 06:09:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602482962; bh=GPU8CP6xKnWURBquscB890UF3K7DVSENbbTjU0EOU3A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=tRrqp9ejoDLiLlMt9hFR3OU0ZPb1vWuFzb3V60ffNIKMBqTIH496h6d3RtHnuOBx7 pedjixHvpMEHkMIvXgDnUuWrHCUCZHzfl0pYQfoF4jU7Xp6Hdzxgo1TplBIi3HFdeA pKWDT2N1cFOHdkuaEYNC6Tiwp7VsAh5EQ84xhqYs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726931AbgJLGJV (ORCPT ); Mon, 12 Oct 2020 02:09:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:46330 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726337AbgJLGJV (ORCPT ); Mon, 12 Oct 2020 02:09:21 -0400 Received: from localhost (unknown [122.182.245.197]) (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 6BDB920757; Mon, 12 Oct 2020 06:09:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602482961; bh=GPU8CP6xKnWURBquscB890UF3K7DVSENbbTjU0EOU3A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=prFNN/Lgyqvvw6oyH5tHsdNyhvz7J9fnspEpav3BNtPSmXWEHte305llkJ9+etXiM 2Zvxj4RuV2Vc2NenmjoWKYzrHqTVnxkWVhxw/itvpB+3ymUqEHmZrdEcQkX6oU8+VR 1Gai7wI58vNqj1NZZm/xU2I3LEScUvfdsyQb0lLk= Date: Mon, 12 Oct 2020 11:39:16 +0530 From: Vinod Koul To: Peter Ujfalusi Cc: dmaengine@vger.kernel.org, Rob Herring , Bjorn Andersson , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/3] dmaengine: add peripheral configuration Message-ID: <20201012060916.GI2968@vkoul-mobl> References: <20201008123151.764238-1-vkoul@kernel.org> <20201008123151.764238-3-vkoul@kernel.org> <20201009103019.GD2968@vkoul-mobl> <20201009111515.GF2968@vkoul-mobl> <13fdee71-5060-83fc-d69d-8ec73f82fac4@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <13fdee71-5060-83fc-d69d-8ec73f82fac4@ti.com> Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 09-10-20, 14:29, Peter Ujfalusi wrote: > > > On 09/10/2020 14.15, Vinod Koul wrote: > >>> If for any any reason subsequent txn is for different direction, I would > >>> expect that parameters are set again before prep_ calls > >> > >> But in DEV_TO_DEV? > > > > Do we support that :D > > > >> If we have two peripherals, both needs config: > >> p1_config and p2_config > >> > >> What and how would one use the single peripheral_config? > > > > Since the config is implementation specific, I do not think it limits. > > You may create > > > > struct peter_config { > > struct p1_config; > > struct p2_config; > > }; > > The use case is: > MEM -DMA-> P1 -DMA-> P2 > or > P2 -DMA-> P1 -DMA-> MEM > or > MEM -DMA-> P2 > or > P2 -DMA-> MEM > or > MEM -DMA-> P1 -DMA-> MEM > > How would the DMA guess what it should do? How would the independent P1 > and P2 would know how to set up the config? As I said, we do not support DEV_TO_DEV yet :) Question is how would p1<-->p2 look, will p1 initiate a DMA txn or p2..? who will configure these.. Do you have a real world example in horizon... -- ~Vinod