From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752374AbcD3Sif (ORCPT ); Sat, 30 Apr 2016 14:38:35 -0400 Received: from mail-wm0-f53.google.com ([74.125.82.53]:37952 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751225AbcD3Sid (ORCPT ); Sat, 30 Apr 2016 14:38:33 -0400 Date: Sat, 30 Apr 2016 19:38:28 +0100 From: Sudip Mukherjee To: Guenter Roeck 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 Subject: Re: [PATCH] watchdog: dw_wdt: dont build for avr32 Message-ID: <20160430183828.GC25043@sudip-laptop> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160412180128.GA6965@roeck-us.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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! 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