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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 ACA06C433FF for ; Sun, 11 Aug 2019 19:52:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76BD120820 for ; Sun, 11 Aug 2019 19:52:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726011AbfHKTwi (ORCPT ); Sun, 11 Aug 2019 15:52:38 -0400 Received: from bmailout1.hostsharing.net ([83.223.95.100]:47537 "EHLO bmailout1.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725870AbfHKTwi (ORCPT ); Sun, 11 Aug 2019 15:52:38 -0400 Received: from h08.hostsharing.net (h08.hostsharing.net [83.223.95.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.hostsharing.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (not verified)) by bmailout1.hostsharing.net (Postfix) with ESMTPS id 1B83B30000CC1; Sun, 11 Aug 2019 21:52:36 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id DB4F2233E81; Sun, 11 Aug 2019 21:52:35 +0200 (CEST) Date: Sun, 11 Aug 2019 21:52:35 +0200 From: Lukas Wunner To: Stefan Wahren Cc: Mark Brown , Vinod Koul , linux-spi@vger.kernel.org, dmaengine@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com, Eric Anholt , Nuno Sa , Martin Sperl , Noralf Tronnes , Robert Jarzmik , Florian Kauer , Florian Fainelli , Ray Jui , Scott Branden Subject: Re: [PATCH 00/10] Raspberry Pi SPI speedups Message-ID: <20190811195235.gojfdgubq7zheino@wunner.de> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org On Sun, Aug 11, 2019 at 09:50:17PM +0200, Stefan Wahren wrote: > Am 03.08.19 um 12:10 schrieb Lukas Wunner: > > So far the BCM2835 SPI driver cannot cope with TX-only and RX-only > > transfers (rx_buf or tx_buf is NULL) when using DMA: It relies on > > the SPI core to convert them to full-duplex transfers by allocating > > and DMA-mapping a dummy rx_buf or tx_buf. This costs performance. > > > > Resolve by pre-allocating reusable DMA descriptors which cyclically > > clear the RX FIFO (for TX-only transfers) or zero-fill the TX FIFO > > (for RX-only transfers). Patch [07/10] provides some numbers for > > the achieved latency improvement and CPU time reduction with an > > SPI Ethernet controller. SPI displays should see a similar speedup. > > I've also made an effort to reduce peripheral and memory bus accesses. > > i know the BCM2711 / Raspberry Pi 4 isn't upstreamed yet, but this > series hasn't been tested with RPi 4? No, I only have the CM1 and CM3 at my disposal for testing, the series seemed to work fine on both. Thanks, Lukas