From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vinod Koul Subject: Re: [PATCH v2 02/13] dmaengine: pl330: Add quirk 'arm,pl330-periph-burst' Date: Wed, 24 Jun 2020 13:49:29 +0530 Message-ID: <20200624081929.GU2324254@vkoul-mobl> References: <1591665267-37713-1-git-send-email-sugar.zhang@rock-chips.com> <1591665267-37713-3-git-send-email-sugar.zhang@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1591665267-37713-3-git-send-email-sugar.zhang@rock-chips.com> Sender: linux-kernel-owner@vger.kernel.org To: Sugar Zhang Cc: Heiko Stuebner , linux-rockchip@lists.infradead.org, Dan Williams , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-rockchip.vger.kernel.org On 09-06-20, 09:14, Sugar Zhang wrote: > This patch adds the qurik to use busrt transfers only s/busrt/burst > for pl330 controller, even for request with a length of 1. > > Although, the correct way should be: if the peripheral request > length is 1, the peripheral should use SINGLE request, and then > notify the dmac using SINGLE mode by src/dst_maxburst with 1. > > For example, on the Rockchip SoCs, all the peripherals can use > SINGLE or BURST request by setting GRF registers. it is possible > that if these peripheral drivers are used only for Rockchip SoCs. > Unfortunately, it's not, such as dw uart, which is used so widely, > and we can't set src/dst_maxburst according to the SoCs' specific > to compatible with all the other SoCs. > > So, for convenience, all the peripherals are set as BURST request > by default on the Rockchip SoCs. even for request with a length of 1. > the current pl330 driver will perform SINGLE transfer if the client's > maxburst is 1, which still should be working according to chapter 2.6.6 > of datasheet which describe how DMAC performs SINGLE transfers for > a BURST request. unfortunately, it's broken on the Rockchip SoCs, s/unfortunately/Unfortunately > which support only matching transfers, such as BURST transfer for > BURST request, SINGLE transfer for SINGLE request. > > Finaly, we add the quirk to specify pl330 to use burst transfers only. s/Finaly/Finally Below looks fine, pls reorder the series and have binding patch come first and then the use of binding. Below looks fine though -- ~Vinod