Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 3/5] watchdog: sp805: set WDOG_HW_RUNNING when appropriate
To:     Robin Murphy <robin.murphy@arm.com>,
        Scott Branden <scott.branden@broadcom.com>,
        Guenter Roeck <linux@roeck-us.net>
Cc:     Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org,
        linux-watchdog@vger.kernel.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        bcm-kernel-feedback-list@broadcom.com,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Frank Rowand <frowand.list@gmail.com>,
        linux-arm-kernel@lists.infradead.org
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>
 <76d47e02-7a5f-3fc2-3905-cd4aa03ac69c@arm.com>
From:   Ray Jui <ray.jui@broadcom.com>
Message-ID: <5a996888-d3d3-9ae6-e438-5de4d5e3ea32@broadcom.com>
Date:   Wed, 23 May 2018 09:29:23 -0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.8.0
MIME-Version: 1.0
In-Reply-To: <76d47e02-7a5f-3fc2-3905-cd4aa03ac69c@arm.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Robin,

On 5/23/2018 4:48 AM, Robin Murphy wrote:
> 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 <ray.jui@broadcom.com>
>>>>> Reviewed-by: Vladimir Olovyannikov 
>>>>> <vladimir.olovyannikov@broadcom.com>
>>>>> Reviewed-by: Scott Branden <scott.branden@broadcom.com>
>>>>> ---
>>>>>   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 (<boolean condition>)
>          return true;
>      else
>          return false;
> 
> still looks really dumb, though, and IMO is actually harder to read than 
> just "return <boolean condition>;" because it forces you to stop and 
> double-check that the logic is, in fact, only doing the obvious thing.

If you can propose a way to modify my original code above to make it 
more readable, I'm fine to make the change.

As I mentioned, I don't think the following change proposed by Guenter 
will work due to the reason I pointed out:

return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));

> 
> 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