From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Murphy Subject: Re: [PATCH 3/5] watchdog: sp805: set WDOG_HW_RUNNING when appropriate Date: Wed, 23 May 2018 12:48:10 +0100 Message-ID: <76d47e02-7a5f-3fc2-3905-cd4aa03ac69c@arm.com> References: <1527014840-21236-1-git-send-email-ray.jui@broadcom.com> <1527014840-21236-4-git-send-email-ray.jui@broadcom.com> <20180522205457.GA16363@roeck-us.net> <0d92b9e9-a3d1-6e91-8371-b5ed3a83e399@broadcom.com> <00c121ea-d197-93b8-2f56-bcca963f70fb@broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <00c121ea-d197-93b8-2f56-bcca963f70fb@broadcom.com> Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Scott Branden , Ray Jui , Guenter Roeck Cc: Mark Rutland , devicetree@vger.kernel.org, linux-watchdog@vger.kernel.org, Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Rob Herring , bcm-kernel-feedback-list@broadcom.com, Wim Van Sebroeck , Frank Rowand , linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On 23/05/18 08:52, Scott Branden wrote: > > > On 18-05-22 04:24 PM, Ray Jui wrote: >> Hi Guenter, >> >> On 5/22/2018 1:54 PM, Guenter Roeck wrote: >>> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote: >>>> If the watchdog hardware is already enabled during the boot process, >>>> when the Linux watchdog driver loads, it should reset the watchdog and >>>> tell the watchdog framework. As a result, ping can be generated from >>>> the watchdog framework, until the userspace watchdog daemon takes over >>>> control >>>> >>>> Signed-off-by: Ray Jui >>>> Reviewed-by: Vladimir Olovyannikov >>>> Reviewed-by: Scott Branden >>>> --- >>>>   drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++ >>>>   1 file changed, 22 insertions(+) >>>> >>>> diff --git a/drivers/watchdog/sp805_wdt.c >>>> b/drivers/watchdog/sp805_wdt.c >>>> index 1484609..408ffbe 100644 >>>> --- a/drivers/watchdog/sp805_wdt.c >>>> +++ b/drivers/watchdog/sp805_wdt.c >>>> @@ -42,6 +42,7 @@ >>>>       /* control register masks */ >>>>       #define    INT_ENABLE    (1 << 0) >>>>       #define    RESET_ENABLE    (1 << 1) >>>> +    #define    ENABLE_MASK    (INT_ENABLE | RESET_ENABLE) >>>>   #define WDTINTCLR        0x00C >>>>   #define WDTRIS            0x010 >>>>   #define WDTMIS            0x014 >>>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0); >>>>   MODULE_PARM_DESC(nowayout, >>>>           "Set to 1 to keep watchdog running after device release"); >>>>   +/* returns true if wdt is running; otherwise returns false */ >>>> +static bool wdt_is_running(struct watchdog_device *wdd) >>>> +{ >>>> +    struct sp805_wdt *wdt = watchdog_get_drvdata(wdd); >>>> + >>>> +    if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) == >>>> +        ENABLE_MASK) >>>> +        return true; >>>> +    else >>>> +        return false; >>> >>>     return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK)); >>> >> >> Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE); >> therefore, a simple !!(expression) would not work? That is, the masked >> result needs to be compared against the mask again to ensure both bits >> are set, right? > Ray - your original code looks correct to me.  Easier to read and less > prone to errors as shown in the attempted translation to a single > statement. if () return true; else return false; still looks really dumb, though, and IMO is actually harder to read than just "return ;" because it forces you to stop and double-check that the logic is, in fact, only doing the obvious thing. Robin. p.s. No thanks for making me remember the mind-boggling horror of briefly maintaining part of this legacy codebase... :P $ grep -r '? true : false' --include=*.cpp . | wc -l 951