From patchwork Thu Feb 17 14:12:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yun Zhou X-Patchwork-Id: 12750240 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CD7DC433FE for ; Thu, 17 Feb 2022 14:12:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241749AbiBQOM5 (ORCPT ); Thu, 17 Feb 2022 09:12:57 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:46602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241353AbiBQOM4 (ORCPT ); Thu, 17 Feb 2022 09:12:56 -0500 Received: from mail1.wrs.com (unknown-3-146.windriver.com [147.11.3.146]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64F922905BD; Thu, 17 Feb 2022 06:12:40 -0800 (PST) Received: from mail.windriver.com (mail.wrs.com [147.11.1.11]) by mail1.wrs.com (8.15.2/8.15.2) with ESMTPS id 21HECbON027478 (version=TLSv1.1 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL); Thu, 17 Feb 2022 06:12:37 -0800 Received: from ala-exchng01.corp.ad.wrs.com (ala-exchng01.corp.ad.wrs.com [147.11.82.252]) by mail.windriver.com (8.15.2/8.15.2) with ESMTPS id 21HECbwB022537 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 17 Feb 2022 06:12:37 -0800 (PST) Received: from ALA-EXCHNG02.corp.ad.wrs.com (147.11.82.254) by ala-exchng01.corp.ad.wrs.com (147.11.82.252) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2242.12; Thu, 17 Feb 2022 06:12:36 -0800 Received: from ala-exchng01.corp.ad.wrs.com (147.11.82.252) by ALA-EXCHNG02.corp.ad.wrs.com (147.11.82.254) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Thu, 17 Feb 2022 06:12:36 -0800 Received: from pek-lpd-ccm3.wrs.com (128.224.156.163) by ala-exchng01.corp.ad.wrs.com (147.11.82.252) with Microsoft SMTP Server id 15.1.2242.12 via Frontend Transport; Thu, 17 Feb 2022 06:12:35 -0800 From: Yun Zhou To: , CC: , , , Subject: [v2][PATCH] spi: use specific last_cs instead of last_cs_enable Date: Thu, 17 Feb 2022 22:12:34 +0800 Message-ID: <20220217141234.72737-1-yun.zhou@windriver.com> X-Mailer: git-send-email 2.26.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Commit d40f0b6f2e21 instroduced last_cs_enable to avoid setting chipselect if it's not necessary, but it also introduces a bug. The chipselect may not be set correctly on multi-device SPI busses. The reason is that we can't judge the chipselect by bool last_cs_enable, since chipselect may be modified after other devices were accessed. So we should record the specific state of chipselect in case of confusion. Signed-off-by: Yun Zhou --- drivers/spi/spi.c | 8 ++++++-- include/linux/spi/spi.h | 5 +++-- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 4599b121d744..d054229ffdda 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -936,13 +936,14 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force) * Avoid calling into the driver (or doing delays) if the chip select * isn't actually changing from the last time this was called. */ - if (!force && (spi->controller->last_cs_enable == enable) && + if (!force && ((enable && spi->controller->last_cs == spi->chip_select) || + (!enable && spi->controller->last_cs != spi->chip_select)) && (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH))) return; trace_spi_set_cs(spi, activate); - spi->controller->last_cs_enable = enable; + spi->controller->last_cs = enable ? spi->chip_select : -1; spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH; if ((spi->cs_gpiod || gpio_is_valid(spi->cs_gpio) || @@ -2980,6 +2981,9 @@ int spi_register_controller(struct spi_controller *ctlr) goto free_bus_id; } + /* setting last_cs to -1 means no chip selected */ + ctlr->last_cs = -1; + status = device_add(&ctlr->dev); if (status < 0) goto free_bus_id; diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 7ab3fed7b804..5a54ea354053 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -373,7 +373,8 @@ extern struct spi_device *spi_new_ancillary_device(struct spi_device *spi, u8 ch * @cur_msg_prepared: spi_prepare_message was called for the currently * in-flight message * @cur_msg_mapped: message has been mapped for DMA - * @last_cs_enable: was enable true on the last call to set_cs. + * @last_cs: the last chip_select that is recorded by set_cs, -1 on non chip + * selected * @last_cs_mode_high: was (mode & SPI_CS_HIGH) true on the last call to set_cs. * @xfer_completion: used by core transfer_one_message() * @busy: message pump is busy @@ -611,7 +612,7 @@ struct spi_controller { bool auto_runtime_pm; bool cur_msg_prepared; bool cur_msg_mapped; - bool last_cs_enable; + char last_cs; bool last_cs_mode_high; bool fallback; struct completion xfer_completion;