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Date: Fri, 17 Feb 2017 16:22:01 +0100 From: Alexandre Belloni <alexandre.belloni@...e-electrons.com> To: Guenter Roeck <linux@...ck-us.net> Cc: Wim Van Sebroeck <wim@...ana.be>, Nicolas Ferre <nicolas.ferre@...el.com>, linux-watchdog@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2 3/3] watchdog: sama5d4: Implement resume hook On 17/02/2017 at 06:47:03 -0800, Guenter Roeck wrote: > On 02/16/2017 11:30 AM, Alexandre Belloni wrote: > > When resuming for the deepest state on sama5d2, it is necessary to restore > > MR as the registers are lost. > > > > Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com> > > --- > > Changes in v2: > > - cache mr beofre suspending > > > > drivers/watchdog/sama5d4_wdt.c | 32 ++++++++++++++++++++++++++++++++ > > 1 file changed, 32 insertions(+) > > > > diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c > > index 2a60251806d2..5ddeb4803dc3 100644 > > --- a/drivers/watchdog/sama5d4_wdt.c > > +++ b/drivers/watchdog/sama5d4_wdt.c > > @@ -28,6 +28,7 @@ > > struct sama5d4_wdt { > > struct watchdog_device wdd; > > void __iomem *reg_base; > > + u32 mr; > > Makes me wonder if we shouldn't just retain the original 'config' > (and maybe rename it to 'mr). After all, it _is_ used now. > > > }; > > > > static int wdt_timeout = WDT_DEFAULT_TIMEOUT; > > @@ -248,11 +249,42 @@ static const struct of_device_id sama5d4_wdt_of_match[] = { > > }; > > MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match); > > > > +#ifdef CONFIG_PM_SLEEP > > +static int sama5d4_wdt_suspend(struct device *dev) > > +{ > > + struct sama5d4_wdt *wdt = dev_get_drvdata(dev); > > + > > + wdt->mr = wdt_read(wdt, AT91_WDT_MR); > > + > > Wouldn't you want to stop the watchdog here if it is running, > ie set AT91_WDT_WDDIS ? > Some existing customers want the watchdog to continue to run while the system is suspended. > > + return 0; > > +} > > + > > +static int sama5d4_wdt_resume(struct device *dev) > > +{ > > + struct sama5d4_wdt *wdt = dev_get_drvdata(dev); > > + u32 reg; > > + > > + reg = wdt_read(wdt, AT91_WDT_MR); > > + if (reg & AT91_WDT_WDDIS) > > + wdt_write(wdt, AT91_WDT_MR, reg & ~AT91_WDT_WDDIS); > > + > > + wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS); > > Is that necessary ? Why not just write wdt->mr unconditionally ? > Because you can change WDV and WDD *OR* WDDIS but not both at the same time. -- Alexandre Belloni, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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