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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 CB6AEC38A2A for ; Sat, 9 May 2020 01:12:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6B9D218AC for ; Sat, 9 May 2020 01:12:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728479AbgEIBMv (ORCPT ); Fri, 8 May 2020 21:12:51 -0400 Received: from cmccmta1.chinamobile.com ([221.176.66.79]:3528 "EHLO cmccmta1.chinamobile.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727828AbgEIBMv (ORCPT ); Fri, 8 May 2020 21:12:51 -0400 Received: from spf.mail.chinamobile.com (unknown[172.16.121.11]) by rmmx-syy-dmz-app01-12001 (RichMail) with SMTP id 2ee15eb60383602-60882; Sat, 09 May 2020 09:12:35 +0800 (CST) X-RM-TRANSID: 2ee15eb60383602-60882 X-RM-TagInfo: emlType=0 X-RM-SPAM-FLAG: 00000000 Received: from [172.20.145.40] (unknown[112.25.154.146]) by rmsmtp-syy-appsvr06-12006 (RichMail) with SMTP id 2ee65eb6038203c-643e9; Sat, 09 May 2020 09:12:35 +0800 (CST) X-RM-TRANSID: 2ee65eb6038203c-643e9 Subject: Re: [PATCH] USB: host: ehci: Add error handlinginehci_mxc_drv_probe() To: Sergei Shtylyov Cc: Greg KH , stern@rowland.harvard.edu, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200508114453.15436-1-tangbin@cmss.chinamobile.com> <20200508114858.GA4085349@kroah.com> <20200508143110.GA447591@kroah.com> <107353c0-09f2-858d-2a87-498e2d8584c6@cmss.chinamobile.com> <66a6bbca-4218-fb71-7284-37f73d5a3c58@cogentembedded.com> From: Tang Bin Message-ID: <012c911d-e877-d7b8-60ab-2e70e67e62cb@cmss.chinamobile.com> Date: Sat, 9 May 2020 09:13:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <66a6bbca-4218-fb71-7284-37f73d5a3c58@cogentembedded.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sergei: On 2020/5/9 4:27, Sergei Shtylyov wrote: > On 05/08/2020 06:03 PM, Tang Bin wrote: > >>>>> On Fri, May 08, 2020 at 07:44:53PM +0800, Tang Bin wrote: >>>>>> The function ehci_mxc_drv_probe() does not perform sufficient error >>>>>> checking after executing platform_get_irq(), thus fix it. >>>>>> >>>>>> Fixes: 7e8d5cd93fa ("USB: Add EHCI support for MX27 and MX31 based boards") >>>>>> Signed-off-by: Zhang Shengju >>>>>> Signed-off-by: Tang Bin >>>>>> --- >>>>>> drivers/usb/host/ehci-mxc.c | 2 ++ >>>>>> 1 file changed, 2 insertions(+) >>>>>> >>>>>> diff --git a/drivers/usb/host/ehci-mxc.c b/drivers/usb/host/ehci-mxc.c >>>>>> index a1eb5ee77..a0b42ba59 100644 >>>>>> --- a/drivers/usb/host/ehci-mxc.c >>>>>> +++ b/drivers/usb/host/ehci-mxc.c >>>>>> @@ -50,6 +50,8 @@ static int ehci_mxc_drv_probe(struct platform_device *pdev) >>>>>> } >>>>>> irq = platform_get_irq(pdev, 0); >>>>>> + if (irq < 0) >>>>>> + return irq; >>>>> <= ? >>>> In the file 'drivers/base/platform.c'， the function platform_get_irq() is >>>> explained and used as follows: >>>> >>>> * Gets an IRQ for a platform device and prints an error message if >>>> finding the >>>> * IRQ fails. Device drivers should check the return value for errors so >>>> as to >>>> * not pass a negative integer value to the request_irq() APIs. >>>> * >>>> * Example: >>>> * int irq = platform_get_irq(pdev, 0); >>>> * if (irq < 0) >>>> * return irq; >>>> * >>>> * Return: IRQ number on success, negative error number on failure. >>>> >>>> And in my hardware experiment, even if I set the irq failed deliberately in >>>> the DTS, the returned value is negative instead of zero. >>> Please read the thread at >>> https://lore.kernel.org/r/20200501224042.141366-1-helgaas%40kernel.org >>> for more details about this. >>> >> Great, It looks beautiful, finally someone took a knife to the file 'platform.c'. > I thought I did that already couple years ago, when returned 0 from platform_get_irq() could mean both IRQ # and error... :-) Can you tell me what platform can returned 0? I want to do this test in the hardware. >> I have been studied this place for a long time, and don't know what platform can return 0, which made me curious. >> >> So the example should be: >> >> * int irq = platform_get_irq(pdev, 0); >> * if (irq <= 0) >> * return irq; > And you then return 0 (success) as if your probe() succeeded. Congratulations! :-P Thanks, Tang Bin