From mboxrd@z Thu Jan  1 00:00:00 1970
From: ray.jui@broadcom.com (Ray Jui)
Date: Wed, 23 May 2018 09:29:23 -0700
Subject: [PATCH 3/5] watchdog: sp805: set WDOG_HW_RUNNING when appropriate
In-Reply-To: <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>
 <76d47e02-7a5f-3fc2-3905-cd4aa03ac69c@arm.com>
Message-ID: <5a996888-d3d3-9ae6-e438-5de4d5e3ea32@broadcom.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

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