Messages in this thread | | | Subject | Re: [PATCH v2 3/3] watchdog: sama5d4: Implement resume hook | From | Guenter Roeck <> | Date | Sun, 19 Feb 2017 09:05:15 -0800 |
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On 02/17/2017 07:22 AM, Alexandre Belloni wrote: > 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@free-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. >
Odd hardware ;-). Please add a comment explaining why the watchdog isn't stopped on suspend, and why the AT91_WDT_MR has to be reprogrammed on resume.
Thanks, Guenter
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