From patchwork Mon Sep 10 11:35:27 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 10594017 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 67245921 for ; Mon, 10 Sep 2018 11:35:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 563B728CF7 for ; Mon, 10 Sep 2018 11:35:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4A4AC28D61; Mon, 10 Sep 2018 11:35:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A142528CF7 for ; Mon, 10 Sep 2018 11:35:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728279AbeIJQ3M (ORCPT ); Mon, 10 Sep 2018 12:29:12 -0400 Received: from heliosphere.sirena.org.uk ([172.104.155.198]:39452 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727727AbeIJQ3L (ORCPT ); Mon, 10 Sep 2018 12:29:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=Date:Message-Id:In-Reply-To: Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Id:List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner: List-Archive; bh=DoUcJG9luRrXKH3x8mt/5XhuFGTA1IKdyx7ZWPQH7JU=; b=IhOjRdcnAwSd Vg6NV64xSnT4/SJIT0m0qSbcXpwxyLR1cuqdke4BSol/8wThiCYpsfJW4WGTIOTaTR21GUt+E3hzx e2Xbpv7CyMzz03m58Zrqu5lVpNR5Ti1BRHZo6OMWS82ovNGaKeRXik0cw5iqFWkmwaGew4BM6H+Sy rFh2A=; Received: from cpc102320-sgyl38-2-0-cust46.18-2.cable.virginm.net ([82.37.168.47] helo=debutante.sirena.org.uk) by heliosphere.sirena.org.uk with esmtpa (Exim 4.89) (envelope-from ) id 1fzKTX-0001vx-LU; Mon, 10 Sep 2018 11:35:27 +0000 Received: by debutante.sirena.org.uk (Postfix, from userid 1000) id 6BFE51122D51; Mon, 10 Sep 2018 12:35:27 +0100 (BST) From: Mark Brown To: Linus Walleij Cc: Andrzej Hajda , Lorenzo Bianconi , Mark Brown , linux-spi@vger.kernel.org Subject: Applied "spi: gpio: No MISO does not imply no RX" to the spi tree In-Reply-To: Message-Id: <20180910113527.6BFE51122D51@debutante.sirena.org.uk> Date: Mon, 10 Sep 2018 12:35:27 +0100 (BST) Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The patch spi: gpio: No MISO does not imply no RX has been applied to the spi tree at https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted. You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed. If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced. Please add any relevant lists and maintainers to the CCs when replying to this mail. Thanks, Mark From abf5feef3ff0cefade0c76be53b59e55fdd46093 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Mon, 10 Sep 2018 00:28:05 +0200 Subject: [PATCH] spi: gpio: No MISO does not imply no RX There is a logical problem in spi-gpio with host just assigning a MOSI line and no MISO: this is interpreted as the host cannot do RX and the host is flagged with SPI_MASTER_NO_RX. This is wrong: since GPIO lines can switch direction, in 3WIRE operation the host will simply reverse the direction of the GPIO line and start reading from it, there is even code for doing this in the driver, but it went unnoticed because it was tested by using a master with 4 wires but a device using just 3 wires. Remove the offending flag. Cc: Andrzej Hajda Cc: Lorenzo Bianconi Signed-off-by: Linus Walleij Signed-off-by: Mark Brown --- drivers/spi/spi-gpio.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c index d0c6d71b6c0f..a2b08b464857 100644 --- a/drivers/spi/spi-gpio.c +++ b/drivers/spi/spi-gpio.c @@ -295,9 +295,11 @@ static int spi_gpio_request(struct device *dev, spi_gpio->miso = devm_gpiod_get_optional(dev, "miso", GPIOD_IN); if (IS_ERR(spi_gpio->miso)) return PTR_ERR(spi_gpio->miso); - if (!spi_gpio->miso) - /* HW configuration without MISO pin */ - *mflags |= SPI_MASTER_NO_RX; + /* + * No setting SPI_MASTER_NO_RX here - if there is only a MOSI + * pin connected the host can still do RX by changing the + * direction of the line. + */ spi_gpio->sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW); if (IS_ERR(spi_gpio->mosi)) @@ -423,7 +425,7 @@ static int spi_gpio_probe(struct platform_device *pdev) spi_gpio->bitbang.chipselect = spi_gpio_chipselect; spi_gpio->bitbang.set_line_direction = spi_gpio_set_direction; - if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) { + if ((master_flags & SPI_MASTER_NO_TX) == 0) { spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0; spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1; spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;