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=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 9D532C433E2 for ; Sun, 30 Aug 2020 16:39:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DD7A20714 for ; Sun, 30 Aug 2020 16:39:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726924AbgH3Qjs (ORCPT ); Sun, 30 Aug 2020 12:39:48 -0400 Received: from hostingweb31-40.netsons.net ([89.40.174.40]:57002 "EHLO hostingweb31-40.netsons.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726478AbgH3QjH (ORCPT ); Sun, 30 Aug 2020 12:39:07 -0400 Received: from [78.134.86.56] (port=34202 helo=melee.dev.aim) by hostingweb31.netsons.net with esmtpa (Exim 4.93) (envelope-from ) id 1kCQMC-000E3G-Dm; Sun, 30 Aug 2020 18:39:04 +0200 From: Luca Ceresoli To: linux-fpga@vger.kernel.org Cc: Luca Ceresoli , Moritz Fischer , Tom Rix , Michal Simek , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Anatolij Gustschin Subject: [PATCH v4 3/5] fpga manager: xilinx-spi: fix write_complete timeout handling Date: Sun, 30 Aug 2020 18:38:48 +0200 Message-Id: <20200830163850.8380-3-luca@lucaceresoli.net> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200830163850.8380-1-luca@lucaceresoli.net> References: <20200830163850.8380-1-luca@lucaceresoli.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - hostingweb31.netsons.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lucaceresoli.net X-Get-Message-Sender-Via: hostingweb31.netsons.net: authenticated_id: luca+lucaceresoli.net/only user confirmed/virtual account not confirmed X-Authenticated-Sender: hostingweb31.netsons.net: luca@lucaceresoli.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If this routine sleeps because it was scheduled out, it might miss DONE going asserted and consider it a timeout. This would potentially make the code return an error even when programming succeeded. Rewrite the loop to always check DONE after checking if timeout expired so this cannot happen anymore. While there, also add error checking for gpiod_get_value(). Also avoid checking the DONE GPIO in two places, which would make the error-checking code duplicated and more annoying. The new loop it written to still guarantee that we apply 8 extra CCLK cycles after DONE has gone asserted, which is required by the hardware. Reported-by: Tom Rix Reviewed-by: Tom Rix Signed-off-by: Luca Ceresoli --- Changes in v4: - add Reviewed-by Tom Rix - fix uninitialized variable (Reported-by: kernel test robot ) Changes in v3: - completely rewrite the loop after Tom pointed out the 'sleep' bug This patch is new in v2 --- drivers/fpga/xilinx-spi.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c index 01f494172379..fba8eb4866a7 100644 --- a/drivers/fpga/xilinx-spi.c +++ b/drivers/fpga/xilinx-spi.c @@ -151,22 +151,29 @@ static int xilinx_spi_write_complete(struct fpga_manager *mgr, struct fpga_image_info *info) { struct xilinx_spi_conf *conf = mgr->priv; - unsigned long timeout; + unsigned long timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us); + bool expired = false; + int done; int ret; - if (gpiod_get_value(conf->done)) - return xilinx_spi_apply_cclk_cycles(conf); + /* + * This loop is carefully written such that if the driver is + * scheduled out for more than 'timeout', we still check for DONE + * before giving up and we apply 8 extra CCLK cycles in all cases. + */ + while (!expired) { + expired = time_after(jiffies, timeout); - timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us); - - while (time_before(jiffies, timeout)) { + done = get_done_gpio(mgr); + if (done < 0) + return done; ret = xilinx_spi_apply_cclk_cycles(conf); if (ret) return ret; - if (gpiod_get_value(conf->done)) - return xilinx_spi_apply_cclk_cycles(conf); + if (done) + return 0; } dev_err(&mgr->dev, "Timeout after config data transfer\n"); -- 2.28.0