From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH 3/5] watchdog: sp805: set WDOG_HW_RUNNING when appropriate Date: Wed, 23 May 2018 11:06:39 -0700 Message-ID: <20180523180639.GA27570@roeck-us.net> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <76d47e02-7a5f-3fc2-3905-cd4aa03ac69c@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Robin Murphy Cc: Scott Branden , Ray Jui , 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 Wed, May 23, 2018 at 12:48:10PM +0100, 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 > >>>>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. > Yes, and I won't accept it, sorry. Guenter > 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