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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 33C89C43381 for ; Sun, 17 Feb 2019 13:17:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EFC2A2192C for ; Sun, 17 Feb 2019 13:17:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728990AbfBQNR1 convert rfc822-to-8bit (ORCPT ); Sun, 17 Feb 2019 08:17:27 -0500 Received: from gloria.sntech.de ([185.11.138.130]:50096 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726511AbfBQNR1 (ORCPT ); Sun, 17 Feb 2019 08:17:27 -0500 Received: from p5b127a91.dip0.t-ipconnect.de ([91.18.122.145] helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gvMJr-000220-Ox; Sun, 17 Feb 2019 14:17:19 +0100 From: Heiko Stuebner To: Katsuhiro Suzuki Cc: linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: dts: rockchip: add HDMI sound node for rk3328-rock64 Date: Sun, 17 Feb 2019 14:17:18 +0100 Message-ID: <15054640.NB91u9fWWK@phil> In-Reply-To: <16f4fcf0-e9c2-e925-e463-282cfff088c7@katsuster.net> References: <20190202043444.9308-1-katsuhiro@katsuster.net> <2275914.n7pQDzs7mT@diego> <16f4fcf0-e9c2-e925-e463-282cfff088c7@katsuster.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Sonntag, 17. Februar 2019, 11:58:36 CET schrieb Katsuhiro Suzuki: > Hello Heiko, > > On 2019/02/12 20:12, Heiko Stübner wrote: > > Hi, > > > > Am Montag, 4. Februar 2019, 13:59:37 CET schrieb Katsuhiro Suzuki: > >> On 2019/02/03 18:06, Heiko Stuebner wrote: > >>> Am Samstag, 2. Februar 2019, 05:34:44 CET schrieb Katsuhiro Suzuki: > >>>> This patch adds HDMI sound (I2S0) node and remove dma properties > >>>> from UART2 node for rock64. > >>>> > >>>> The DMAC of rk3328 can use 8 channels at same time. Currently, total > >>>> > >>>> 7 channels are used as follows: > >>>> - I2S1 2ch > >>>> - UART2 2ch > >>>> - SPDIF 1ch > >>>> - SPI0 2ch > >>>> > >>>> HDMI audio using I2S0 that requires 2ch but DMAC has only 1 channel. > >>>> > >>>> UART2 can work without DMA resources, so this patch removes dma > >>>> allocation for UART2 and reuses it to I2S0. > >>> > >>> I don't follow that description. How can i2s0 re-use the uart2 dma > >>> channels? Looking at the dma table in the TRM, uart2 has channels 6+7 > >>> while i2s0 uses channels 11+12. They should just run concurrently? > >> > >> Sorry for confusing... 6 or 7 is as ID number of slave DMA channel. > >> TRM calls it 'Req number'. Req number 6+7 and 11+12 can work > >> concurrently but TRM says DMAC can transfer 8 DMA channels at same > >> time. So all 16 Req numbers cannot activate at same time. It should > >> be keep less or equal than 8 numbers. > > > > But that "shortcoming" of having more requests than channels is not > > something specific to the pl330, instead most dma controllers have that > > "problem", which seems to get solved by the virt-dma mechanism of > > dmaengine - which pl330 doesn't use so far. (but see pl080 for example) > > > > I understand. I drop these patches. > > > > The devicetree only describes the hardware and is never meant as a > > configuration space for kernel-code shortcomings. > > > > Yes, right. I don't want to use device-tree as configuration space, > so which is better? > > - Fix the pl330 driver first and after that add HDMI-sound node > to device-tree. > - Just add HDMI-sound node to device-tree. If someone (include me) > want to support virt-dma on pl330 driver, they will fix it. > (PL330 will face error but all sounds works fine and UART still > works fine with DMA error) I'd go with this second option :-) . Heiko