From patchwork Fri Apr 16 19:59:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Bauer X-Patchwork-Id: 423068 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 AFED8C433ED for ; Fri, 16 Apr 2021 20:06:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78C6A613CC for ; Fri, 16 Apr 2021 20:06:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244249AbhDPUHM (ORCPT ); Fri, 16 Apr 2021 16:07:12 -0400 Received: from perseus.uberspace.de ([95.143.172.134]:56362 "EHLO perseus.uberspace.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236363AbhDPUHM (ORCPT ); Fri, 16 Apr 2021 16:07:12 -0400 X-Greylist: delayed 400 seconds by postgrey-1.27 at vger.kernel.org; Fri, 16 Apr 2021 16:07:11 EDT Received: (qmail 11258 invoked from network); 16 Apr 2021 20:00:04 -0000 Received: from localhost (HELO localhost) (127.0.0.1) by perseus.uberspace.de with SMTP; 16 Apr 2021 20:00:04 -0000 From: David Bauer To: broonie@kernel.org, linux-spi@vger.kernel.org Subject: [PATCH] spi: sync up initial chipselect state Date: Fri, 16 Apr 2021 21:59:56 +0200 Message-Id: <20210416195956.121811-1-mail@david-bauer.net> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org When initially probing the SPI slave device, the call for disabling an SPI device without the SPI_CS_HIGH flag is not applied, as the condition for checking whether or not the state to be applied equals the one currently set evaluates to true. This however might not necessarily be the case, as the chipselect might be active. Add a force flag to spi_set_cs which allows to override this early exit condition. Set it to false everywhere except when called from spi_setup to sync up the initial CS state. Fixes commit d40f0b6f2e21 ("spi: Avoid setting the chip select if we don't need to") Signed-off-by: David Bauer --- drivers/spi/spi.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index b08efe88ccd6..927c2a28011f 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -795,7 +795,7 @@ int spi_register_board_info(struct spi_board_info const *info, unsigned n) /*-------------------------------------------------------------------------*/ -static void spi_set_cs(struct spi_device *spi, bool enable) +static void spi_set_cs(struct spi_device *spi, bool enable, bool force) { bool enable1 = enable; @@ -803,7 +803,7 @@ static void spi_set_cs(struct spi_device *spi, bool enable) * Avoid calling into the driver (or doing delays) if the chip select * isn't actually changing from the last time this was called. */ - if ((spi->controller->last_cs_enable == enable) && + if (!force && (spi->controller->last_cs_enable == enable) && (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH))) return; @@ -1253,7 +1253,7 @@ static int spi_transfer_one_message(struct spi_controller *ctlr, struct spi_statistics *statm = &ctlr->statistics; struct spi_statistics *stats = &msg->spi->statistics; - spi_set_cs(msg->spi, true); + spi_set_cs(msg->spi, true, false); SPI_STATISTICS_INCREMENT_FIELD(statm, messages); SPI_STATISTICS_INCREMENT_FIELD(stats, messages); @@ -1321,9 +1321,9 @@ static int spi_transfer_one_message(struct spi_controller *ctlr, &msg->transfers)) { keep_cs = true; } else { - spi_set_cs(msg->spi, false); + spi_set_cs(msg->spi, false, false); _spi_transfer_cs_change_delay(msg, xfer); - spi_set_cs(msg->spi, true); + spi_set_cs(msg->spi, true, false); } } @@ -1332,7 +1332,7 @@ static int spi_transfer_one_message(struct spi_controller *ctlr, out: if (ret != 0 || !keep_cs) - spi_set_cs(msg->spi, false); + spi_set_cs(msg->spi, false, false); if (msg->status == -EINPROGRESS) msg->status = ret; @@ -3423,11 +3423,11 @@ int spi_setup(struct spi_device *spi) */ status = 0; - spi_set_cs(spi, false); + spi_set_cs(spi, false, true); pm_runtime_mark_last_busy(spi->controller->dev.parent); pm_runtime_put_autosuspend(spi->controller->dev.parent); } else { - spi_set_cs(spi, false); + spi_set_cs(spi, false, true); } mutex_unlock(&spi->controller->io_mutex);