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 1DA14C433FE for ; Tue, 15 Feb 2022 11:21:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237067AbiBOLVR (ORCPT ); Tue, 15 Feb 2022 06:21:17 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:40600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237036AbiBOLVQ (ORCPT ); Tue, 15 Feb 2022 06:21:16 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B211910819A; Tue, 15 Feb 2022 03:21:03 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 70020B81897; Tue, 15 Feb 2022 11:21:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 538EDC340EB; Tue, 15 Feb 2022 11:20:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644924061; bh=zD0KcG3WVsVW8SnijqwnkAIV1vy0CeKOVswvBGb/SfY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bqTw22UgLjKXV1OKyZd8VKfIV1ywICbAXqRRrNxi+1uy5mKgwfY1ZkF54M0xhBcsP DLemD8FeThImoD0ZxD7c3T/LDfEg+h/iJ3X3sm4tlVKBidFY6lQN1g+onI92QLT04x dZAnmr418sxPReZ/kJhU6wlAO15Vy8XSAj4fNgusDEnzUPkgrEW0ZuhOOez0ERZSzk fjrTMAAWKSf0xbNLFK2qEVJlo5NxjBfmUrYMlHbQzKnsgs3MMqnYXwxhbF5e9PHfW7 pQdeea++IADbHWmBcUJ56RY9hozaxLNNOV1R5CffBYoDY2Ta68eaoMUaeUQwcjyTGQ 5zM4t6WmfU7gA== Date: Tue, 15 Feb 2022 16:50:57 +0530 From: Vinod Koul To: Stefan Wahren Cc: Rob Herring , Florian Fainelli , Nicolas Saenz Julienne , Ray Jui , Scott Branden , bcm-kernel-feedback-list@broadcom.com, dmaengine@vger.kernel.org, Phil Elwell , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Lukas Wunner , linux-rpi-kernel@lists.infradead.org Subject: Re: [PATCH RFC 00/11] dmaengine: bcm2835: add BCM2711 40-bit DMA support Message-ID: References: <1640606743-10993-1-git-send-email-stefan.wahren@i2se.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 23-01-22, 15:08, Stefan Wahren wrote: > Hi, > > Am 27.12.21 um 13:05 schrieb Stefan Wahren: > > The BCM2711 has 4 DMA channels with a 40-bit address range, allowing them > > to access the full 4GB of memory on a Pi 4. This patch series serves as a > > basis for a discussion (just compile tested, so don't expect anything working) > > which include the following points: > > > > * correct DT binding and representation for BCM2711 > > > > According to the vendor DTS [1] the 4 DMA channels are connected to SCB. > > I'm not sure how this is properly adapted to the mainline DT. > > > > * general implementation approach > > > > The vendor approach mapped all the BCM2835 control block bits to the BCM2711 > > layout and the rest of the differences are handled by a lot of is_40bit_channel > > conditions. An advantage of this is the small amount of changes to the driver. > > But on the down side the code is now much harder to understand and maintain. > > > > This series tries to implement this feature in a more cleaner way > > while keeping it in the bcm2835-dma driver. Before this series the driver > > has ~ 1000 lines and after that ~ 1500 lines. > > > > So the question is this approach acceptable? > > > > Patches 1 - 3 are just clean-ups. > > > > Disclaimer: my knowledge about the DMA controller is very limited > > > > More information: > > > > https://datasheets.raspberrypi.com/bcm2711/bcm2711-peripherals.pdf > > > > [1] - https://github.com/raspberrypi/linux/blob/561deffcf471ba0f7bd48541d06a79d5aa38d297/arch/arm/boot/dts/bcm2711-rpi-ds.dtsi#L47 > > [2] - https://github.com/raspberrypi/linux/commit/44364bd140b0bc9187c881fbdc4ee358961059d5 > would be nice to get some input aka gentle ping. Somehow patch 10/11 is appearing split from rest of the series. The series looks fairly okay, dts needs more polishing as Rob indicated -- ~Vinod