From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from bh-25.webhostbox.net ([208.91.199.152]:38888 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751923AbbDCBxJ (ORCPT ); Thu, 2 Apr 2015 21:53:09 -0400 Received: from mailnull by bh-25.webhostbox.net with sa-checked (Exim 4.82) (envelope-from ) id 1YdqnE-0034me-Oj for linux-watchdog@vger.kernel.org; Fri, 03 Apr 2015 01:53:08 +0000 Message-ID: <551DF27A.6060704@roeck-us.net> Date: Thu, 02 Apr 2015 18:52:58 -0700 From: Guenter Roeck MIME-Version: 1.0 To: Andrew Bresticker CC: James Hogan , Wim Van Sebroeck , "linux-watchdog@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Ezequiel Garcia Subject: Re: [PATCH V2 1/3] watchdog: imgpdc: Allow timeout to be set in device-tree References: <1427910196-28568-1-git-send-email-abrestic@chromium.org> <20150401222218.GB13077@jhogan-linux.le.imgtec.org> <551C96AA.2060906@roeck-us.net> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org On 04/02/2015 09:46 AM, Andrew Bresticker wrote: > On Wed, Apr 1, 2015 at 6:08 PM, Guenter Roeck wrote: >> On 04/01/2015 03:22 PM, James Hogan wrote: >>> >>> Hi Andrew, >>> >>> On Wed, Apr 01, 2015 at 10:43:14AM -0700, Andrew Bresticker wrote: >>>> >>>> Since the heartbeat is statically initialized to its default value, >>>> watchdog_init_timeout() will never look in the device-tree for a >>>> timeout-sec value. Instead of statically initializing heartbeat, >>>> fall back to the default timeout value if watchdog_init_timeout() >>>> fails. >>> >>> >>> Whoops. Sorry about that. I wasn't aware that a timeout-sec value was >>> expected. It isn't mentioned in the DT binding documentation for this >>> device :-(. >>> >>>> >>>> Signed-off-by: Andrew Bresticker >>>> Cc: Ezequiel Garcia >>>> Cc: James Hogan >>>> --- >>>> New for v2. >>>> --- >>>> drivers/watchdog/imgpdc_wdt.c | 6 +++--- >>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/drivers/watchdog/imgpdc_wdt.c >>>> b/drivers/watchdog/imgpdc_wdt.c >>>> index 0deaa4f..89b2abc 100644 >>>> --- a/drivers/watchdog/imgpdc_wdt.c >>>> +++ b/drivers/watchdog/imgpdc_wdt.c >>>> @@ -42,7 +42,7 @@ >>>> #define PDC_WDT_MIN_TIMEOUT 1 >>>> #define PDC_WDT_DEF_TIMEOUT 64 >>>> >>>> -static int heartbeat = PDC_WDT_DEF_TIMEOUT; >>>> +static int heartbeat; >>>> module_param(heartbeat, int, 0); >>>> MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds " >>>> "(default=" __MODULE_STRING(PDC_WDT_DEF_TIMEOUT) ")"); >>>> @@ -195,9 +195,9 @@ static int pdc_wdt_probe(struct platform_device >>>> *pdev) >>>> >>>> ret = watchdog_init_timeout(&pdc_wdt->wdt_dev, heartbeat, >>>> &pdev->dev); >>>> if (ret < 0) { >>>> - pdc_wdt->wdt_dev.timeout = pdc_wdt->wdt_dev.max_timeout; >>>> + pdc_wdt->wdt_dev.timeout = PDC_WDT_DEF_TIMEOUT; >>> >>> >>> The watchdog_init_timeout kerneldoc comment suggests that the old value >>> should be the default timeout, i.e. that timeout should be set to >>> PDC_WDT_DEF_TIMEOUT before calling watchdog_init_timeout, rather than >>> whenever ret < 0. >>> >>> Indeed, if heartbeat is set to an invalid non-zero value, >>> watchdog_init_timeout will still try and set timeout from DT, but also >>> still returns -EINVAL regardless of whether that succeeds, and this >>> would incorrectly override the timeout from DT with the hardcoded >>> default. >>> >>>> dev_warn(&pdev->dev, >>>> - "Initial timeout out of range! setting max >>>> timeout\n"); >>>> + "Initial timeout out of range! setting default >>>> timeout\n"); >>> >>> >>> It feels wrong for a presumably safe & normal situation (i.e. no default >>> in DT, which arguably shouldn't contain policy anyway) to show a >>> warning, but it can also show due to an invalid module parameter (or >>> invalid DT property) which is most definitely justified. >>> >> >> Agreed. I would suggest to leave that part alone and set the default prior >> to calling watchdog_init_timeout(). > > Yes, but I think James' concern here was that we'd now get a > dev_warn() in the normal case where no timeout is specified via module > parameter or DT. > My understanding is that watchdog_init_timeout only returns an error if the second parameter is not 0 and invalid, or if the timeout-sec property has been provided and is invalid. I am not entirely sure I understand why you think this is a problem. Can you please explain ? Thanks, Guenter