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,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 AC2B2C433E1 for ; Thu, 27 Aug 2020 19:26:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D833207CD for ; Thu, 27 Aug 2020 19:26:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726246AbgH0T0H (ORCPT ); Thu, 27 Aug 2020 15:26:07 -0400 Received: from hostingweb31-40.netsons.net ([89.40.174.40]:48502 "EHLO hostingweb31-40.netsons.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726236AbgH0T0H (ORCPT ); Thu, 27 Aug 2020 15:26:07 -0400 Received: from [78.134.86.56] (port=44256 helo=[192.168.77.62]) by hostingweb31.netsons.net with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1kBNX9-0008JP-Ii; Thu, 27 Aug 2020 21:26:03 +0200 Subject: Re: [PATCH v2 3/5] fpga manager: xilinx-spi: rework write_complete loop implementation To: Tom Rix , linux-fpga@vger.kernel.org Cc: Moritz Fischer , Michal Simek , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Anatolij Gustschin References: <20200827143249.10973-1-luca@lucaceresoli.net> <20200827143249.10973-3-luca@lucaceresoli.net> <2b8d9ed7-0468-9001-2f8e-386312aae6cb@redhat.com> From: Luca Ceresoli Message-ID: Date: Thu, 27 Aug 2020 21:26:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <2b8d9ed7-0468-9001-2f8e-386312aae6cb@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 X-Authenticated-Sender: hostingweb31.netsons.net: luca@lucaceresoli.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-fpga-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fpga@vger.kernel.org Hi Tom, thanks for the prompt feedback! On 27/08/20 20:59, Tom Rix wrote: > > On 8/27/20 7:32 AM, Luca Ceresoli wrote: >> In preparation to add error checking for gpiod_get_value(), rework >> the loop to avoid the duplication of these lines: >> >> if (gpiod_get_value(conf->done)) >> return xilinx_spi_apply_cclk_cycles(conf); >> >> There is little advantage in this rework with current code. However >> error checking will expand these two lines to five, making code >> duplication more annoying. >> >> Signed-off-by: Luca Ceresoli >> >> --- >> >> This patch is new in v2 >> --- >> drivers/fpga/xilinx-spi.c | 15 ++++++--------- >> 1 file changed, 6 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c >> index 01f494172379..cfc933d70f52 100644 >> --- a/drivers/fpga/xilinx-spi.c >> +++ b/drivers/fpga/xilinx-spi.c >> @@ -151,22 +151,19 @@ 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); >> int ret; >> >> - if (gpiod_get_value(conf->done)) >> - return xilinx_spi_apply_cclk_cycles(conf); >> - >> - timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us); >> + while (true) { >> + if (gpiod_get_value(conf->done)) >> + return xilinx_spi_apply_cclk_cycles(conf); >> >> - while (time_before(jiffies, timeout)) { >> + if (time_after(jiffies, timeout)) >> + break; >> >> ret = xilinx_spi_apply_cclk_cycles(conf); >> if (ret) >> return ret; >> - >> - if (gpiod_get_value(conf->done)) >> - return xilinx_spi_apply_cclk_cycles(conf); >> } > > Do you need another > > if (gpiod_get_value(conf->done)) > return xilinx_spi_apply_cclk_cycles(conf); > > here to cover the chance of sleeping in the loop ? If I got your question correctly: if we get here it's because of a timeout, thus programming has failed (DONE didn't come up after some time), and checking it one more here seems pointless. Does this reply your question? -- Luca