From patchwork Fri Aug 28 19:58:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Ceresoli X-Patchwork-Id: 11743683 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E8690913 for ; Fri, 28 Aug 2020 19:58:52 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C27EB20E65 for ; Fri, 28 Aug 2020 19:58:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="nX22hssM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C27EB20E65 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lucaceresoli.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=cxTSL9Uq9xqbkQRNBLYyapA34iszLx4BY5ozAEMd2Qk=; b=nX22hssM9a5dil/KX8lxsL+Xw 2kifzl9gOiRijMGmBC9D9U8wfRoP1KoevRaMoPdXlgTW7dkZczprzjPAVJSIHoWXSrkodDIKmimdb aKOLA/JSWvv+5fblkuH7V8S5LD9QObktyvxsdacFJT7PnJV9s9sHd10eK61ccHmSriuy84OXTOO6f ojAKZI4zESpeGyEi/zhovq+UmfDcqisGBh4PJupIS+BLDq4RFtr0+8pLFLmQIOQYV/0N9UL2EBLTo EWonJraS5lwu6f+kNnlFzByotvV+nLAK55n6DIXHWZ6SufAftx5XCQoVtADaQmpHIf8aQXtYVC5f7 03NmM+ReA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBkWI-00037r-9R; Fri, 28 Aug 2020 19:58:42 +0000 Received: from hostingweb31-40.netsons.net ([89.40.174.40]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBkW2-00033P-6e for linux-arm-kernel@lists.infradead.org; Fri, 28 Aug 2020 19:58:28 +0000 Received: from [78.134.86.56] (port=54992 helo=melee.dev.aim) by hostingweb31.netsons.net with esmtpa (Exim 4.93) (envelope-from ) id 1kBkVw-0008I1-I6; Fri, 28 Aug 2020 21:58:20 +0200 From: Luca Ceresoli To: linux-fpga@vger.kernel.org Subject: [PATCH v3 3/5] fpga manager: xilinx-spi: fix write_complete timeout handling Date: Fri, 28 Aug 2020 21:58:06 +0200 Message-Id: <20200828195808.27975-3-luca@lucaceresoli.net> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200828195808.27975-1-luca@lucaceresoli.net> References: <20200828195808.27975-1-luca@lucaceresoli.net> MIME-Version: 1.0 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 - lists.infradead.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: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200828_155826_519992_59D1BECC X-CRM114-Status: GOOD ( 15.23 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [89.40.174.40 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tom Rix , Michal Simek , linux-kernel@vger.kernel.org, Moritz Fischer , Luca Ceresoli , Anatolij Gustschin , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.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 Signed-off-by: Luca Ceresoli --- 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..a7b919eb0b2a 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; + 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");