From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vinod Koul Subject: Re: [PATCH v5 2/3] dmaengine: mediatek: Add MediaTek High-Speed DMA controller for MT7622 and MT7623 SoC Date: Fri, 2 Mar 2018 13:47:06 +0530 Message-ID: <20180302081706.GL15443@localhost> References: <20180301082329.GD15443@localhost> <1519900021.8089.136.camel@mtkswgap22> <20180301125649.GH15443@localhost> <1519973271.8089.166.camel@mtkswgap22> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1519973271.8089.166.camel@mtkswgap22> Sender: linux-kernel-owner@vger.kernel.org To: Sean Wang Cc: dan.j.williams@intel.com, robh+dt@kernel.org, mark.rutland@arm.com, dmaengine@vger.kernel.org, devicetree@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Randy Dunlap , Fengguang Wu , Julia Lawall List-Id: devicetree@vger.kernel.org On Fri, Mar 02, 2018 at 02:47:51PM +0800, Sean Wang wrote: > Hi, Vinod > > On Thu, 2018-03-01 at 18:26 +0530, Vinod Koul wrote: > > On Thu, Mar 01, 2018 at 06:27:01PM +0800, Sean Wang wrote: > > > On Thu, 2018-03-01 at 13:53 +0530, Vinod Koul wrote: > > > > On Sun, Feb 18, 2018 at 03:08:30AM +0800, sean.wang@mediatek.com wrote: > > > > > > > > > @@ -0,0 +1,1054 @@ > > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > // Copyright ... > > > > > > > > The copyright line needs to follow SPDX tag line > > > > > > > > > > okay, I will make it reorder and be something like that > > > > > > // SPDX-License-Identifier: GPL-2.0 > > > /* > > > * Copyright (c) 2017-2018 MediaTek Inc. > > > * Author: Sean Wang > > > * > > > * Driver for MediaTek High-Speed DMA Controller > > > * > > > */ > > > > It needs to be: > > > > // SPDX-License-Identifier: GPL-2.0 > > // Copyright (c) 2017-2018 MediaTek Inc. > > > > /* > > * whatever else you want > > */ > > > > The first two lines are in C99 style comment and need to have SPDX tag and > > Copyright info > > Sure, I can do it using C99 style comments at the first two lines. > > In addition, I'm really curious where we can find a reference to the > rule and if it 's a strict rule for all the drivers. > > Because I'm considering whether I should turn other driver into using > the same rule. Yes that seems to be the rule now https://lkml.org/lkml/2017/11/2/715 > > > > > +#define MTK_HSDMA_USEC_POLL 20 > > > > > +#define MTK_HSDMA_TIMEOUT_POLL 200000 > > > > > +#define MTK_HSDMA_DMA_BUSWIDTHS BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) > > > > > > > > Undefined buswidth?? > > > > ?? > > Sorry for I didn't answer the question in the short time. > > After spending some time on a confirmation with design, it is > DMA_SLAVE_BUSWIDTH_4_BYTES and not be configurable. Then it should be DMA_SLAVE_BUSWIDTH_4_BYTES and not DMA_SLAVE_BUSWIDTH_UNDEFINED... > > > > shouldn't we check if next is in range, we can crash if we get bad value > > > > from hardware.. > > > > > > okay, there are checks for next with ddone bit check and null check in > > > the corresponding descriptor as the following. > > > > what if you get bad next value > > > > next is not hardware value. it's maintained by software which is always > between 0 to MTK_DMA_SIZE - 1, and definitely doesn't get a bad value. > > > > > > > > > + rxd = &pc->ring.rxd[next]; > > > > resulting in bad ref here > > rxd is also definitely a good ref not if next is out of range, say you read -1 or 200000? -- ~Vinod