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=-2.5 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 F05E6C0650E for ; Mon, 1 Jul 2019 11:55:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8CF9208CA for ; Mon, 1 Jul 2019 11:55:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728763AbfGALzJ (ORCPT ); Mon, 1 Jul 2019 07:55:09 -0400 Received: from bmailout1.hostsharing.net ([83.223.95.100]:43321 "EHLO bmailout1.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728388AbfGALzI (ORCPT ); Mon, 1 Jul 2019 07:55:08 -0400 Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (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 7BB763001531F; Mon, 1 Jul 2019 13:55:06 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 3BE7E23EF52; Mon, 1 Jul 2019 13:55:06 +0200 (CEST) Date: Mon, 1 Jul 2019 13:55:06 +0200 From: Lukas Wunner To: "Sa, Nuno" Cc: "wahrenst@gmx.net" , "linux-spi@vger.kernel.org" , "bcm-kernel-feedback-list@broadcom.com" , "broonie@kernel.org" , "kernel@martin.sperl.org" , "linux-kernel@vger.kernel.org" , "sbranden@broadcom.com" , "f.fainelli@gmail.com" , "rjui@broadcom.com" , "linux-rpi-kernel@lists.infradead.org" , "eric@anholt.net" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH] spi: spi-bcm2835.c: Fix 3-wire mode Message-ID: <20190701115506.42rr4o4hbuvwytjc@wunner.de> References: <20190628123023.4696-1-nuno.sa@analog.com> <1b932c61-982b-aae0-1fef-3c574e7d17eb@gmx.net> <20190628190022.vya4h2lihm6x2xpb@wunner.de> <54323339606a36febc6a8633a8d3a7db84b975c4.camel@analog.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54323339606a36febc6a8633a8d3a7db84b975c4.camel@analog.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 01, 2019 at 07:24:23AM +0000, Sa, Nuno wrote: > The problem is in spi_map_msg() which > allocates dummy buffers (because of the ctrl flags). As a result, in > bcm2835_spi_transfer_one() we set "cs |= BCM2835_SPI_CS_REN;" when we > want to do tx only. I believe this was the actual problem... I see. In that case, try: /* handle all the 3-wire mode */ - if ((spi->mode & SPI_3WIRE) && (tfr->rx_buf)) + if ((spi->mode & SPI_3WIRE) && (tfr->rx_buf != ctlr->dummy_rx)) cs |= BCM2835_SPI_CS_REN; else cs &= ~BCM2835_SPI_CS_REN; Use master->dummy_rx instead of ctlr->dummy_rx prior to commit 5f336ea53b6b ("spi: bcm2835: Replace spi_master by spi_controller"). This could be something that users of your cape might use on older kernels in lieu of my upcoming patch set to drop MUST_RX / MUST_TX. Thanks, Lukas