Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752787AbbDCCf7 (ORCPT ); Thu, 2 Apr 2015 22:35:59 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:43376 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751335AbbDCCfz (ORCPT ); Thu, 2 Apr 2015 22:35:55 -0400 Message-ID: <551DFC82.6040402@roeck-us.net> Date: Thu, 02 Apr 2015 19:35:46 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 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> <551DF27A.6060704@roeck-us.net> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020202.551DFC8B.0019,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.001 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: C_4847, X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 2 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 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: mailgid no entry from get_relayhosts_entry 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 Content-Length: 5549 Lines: 148 On 04/02/2015 07:16 PM, Andrew Bresticker wrote: > Hi Guenter, > > On Thu, Apr 2, 2015 at 6:52 PM, Guenter Roeck wrote: >> 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 ? > > Unless I've gone completely insane, I'm pretty sure this will return > -EINVAL if timeout_parm is 0 and timeout-sec is not present: > > int watchdog_init_timeout(struct watchdog_device *wdd, > unsigned int timeout_parm, struct device *dev) > { > unsigned int t = 0; > int ret = 0; > > watchdog_check_min_max_timeout(wdd); > > /* try to get the timeout module parameter first */ > if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) { > wdd->timeout = timeout_parm; > return ret; > } > if (timeout_parm) > ret = -EINVAL; > > /* try to get the timeout_sec property */ > if (dev == NULL || dev->of_node == NULL) > return ret; > of_property_read_u32(dev->of_node, "timeout-sec", &t); > if (!watchdog_timeout_invalid(wdd, t) && t) > wdd->timeout = t; > else > ret = -EINVAL; > > return ret; > } > > That said, the behavior you describe makes more sense, so perhaps > watchdog_init_timeout() should be updated to match. > Ah yes, you are right, that last else case. Guess we'll need input from Wim on how to handle this. Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/