From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752182AbcEAAEx (ORCPT ); Sat, 30 Apr 2016 20:04:53 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:56351 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691AbcEAAEw (ORCPT ); Sat, 30 Apr 2016 20:04:52 -0400 Subject: Re: [PATCH] watchdog: dw_wdt: dont build for avr32 To: Sudip Mukherjee References: <1460440303-20640-1-git-send-email-sudipm.mukherjee@gmail.com> <570CF2CB.2050200@roeck-us.net> <570CFA90.4060100@gmail.com> <20160412180128.GA6965@roeck-us.net> <20160430183828.GC25043@sudip-laptop> Cc: Andy Shevchenko , Wim Van Sebroeck , Haavard Skinnemoen , Hans-Christian Egtvedt , "linux-kernel@vger.kernel.org" , kernel-testers@vger.kernel.org, linux-watchdog@vger.kernel.org, Chris Mason From: Guenter Roeck Message-ID: <57254818.5020008@roeck-us.net> Date: Sat, 30 Apr 2016 17:04:40 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160430183828.GC25043@sudip-laptop> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: linux@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: linux@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/30/2016 11:38 AM, Sudip Mukherjee wrote: > On Tue, Apr 12, 2016 at 11:01:28AM -0700, Guenter Roeck wrote: >> On Tue, Apr 12, 2016 at 05:58:20PM +0300, Andy Shevchenko wrote: >>> On Tue, Apr 12, 2016 at 4:39 PM, Sudip Mukherjee >>> wrote: >>>> On Tuesday 12 April 2016 06:36 PM, Guenter Roeck wrote: >>>>> >>>>> On 04/11/2016 10:51 PM, Sudip Mukherjee wrote: >>>>>> >>>>>> The build of avr32 allmodconfig fails with the error: >>>>>> ERROR: "__avr32_udiv64" [drivers/watchdog/kempld_wdt.ko] undefined! >>>>>> >>>>> This means there is a direct 64 bit divide operation in the driver, >>>>> which we should identify and fix. >>> >>> This driver will quite likely never be used on AVR32. Do we need to >>> fix this due to some other architectures? >>> >>>> yes, there is. >>>> >>>> in function: kempld_wdt_set_stage_timeout() >>>> remainder = do_div(stage_timeout64, prescaler); >>> >>>> Any idea how to fix it? >>> >>> Not easy, however, prescaler value is ((1 << 21) - 1) which someone >>> might consider as (1 << 21) with lost in precision. >>> >>> Thus, shift on 20 bits right, add last bit to the value and shift on 1 >>> bit right more. >>> >> Sorry, I am missing something. do_div() should work fine with any 32 bit value >> as divisor, no matter what that value is. Why does it fail here ? And why does >> it work if I pass 0x1fffff as second parameter to do_div() directly ? > > Please let me know what i can do here to help solve the problem. > linux-next continues to fail for avr32, and to make matters worse we > also have the similar problem in btrfs. > > ERROR: "__avr32_udiv64" [fs/btrfs/btrfs.ko] undefined! > ERROR: "__avr32_udiv64" [drivers/watchdog/kempld_wdt.ko] undefined! > Pretty much what I suspected would happen. Oddly enough, the symbol was defined in early avr32 patch sets [1], but dropped in the final commit after some discussion [2]. Makes me wonder if the problem was always known. Guenter > Adding Chris to CC if he has some idea how to solve this error for btrfs. > Build log for next-20160429 is at: > https://travis-ci.org/sudipm-mukherjee/parport/jobs/126581065 > > regards > sudip > --- [1] https://kldp.org/files/linux-2.6.16.11-avr32-20060626.patch_.txt [2] http://fa.linux.kernel.narkive.com/4UhaxiM4/avr32-architecture-patch-against-linux-2-6-18-rc1-available