Hi, Guenter
> Subject: Re: [PATCH V3 1/2] watchdog: imx7ulp: Strictly follow the sequence
> for wdog operations
>
> On Thu, Jul 30, 2020 at 10:03:10AM +0800, Anson Huang wrote:
> > According to reference manual, the i.MX7ULP WDOG's operations except
> > refresh should follow below sequence:
> >
> > 1. disable global interrupts;
> > 2. unlock the wdog and wait unlock bit set; 3. reconfigure the wdog
> > and wait for reconfiguration bit set; 4. enabel global interrupts.
> >
> > Strictly follow the recommended sequence can make it more robust.
> >
> > Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
> > ---
> > changes since V2:
> > - change the wait timeout to 20us according to experiment;
> > - drop WARN_ON when timeout, and check its return value in each caller
> for
> > unlock wait, no need to handle the return value for reconfiguration.
> > ---
> > drivers/watchdog/imx7ulp_wdt.c | 74
> > ++++++++++++++++++++++++++++++++++--------
> > 1 file changed, 61 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/watchdog/imx7ulp_wdt.c
> > b/drivers/watchdog/imx7ulp_wdt.c index 7993c8c..010ddd1 100644
> > --- a/drivers/watchdog/imx7ulp_wdt.c
> > +++ b/drivers/watchdog/imx7ulp_wdt.c
> > @@ -5,6 +5,7 @@
> >
> > #include <linux/clk.h>
> > #include <linux/io.h>
> > +#include <linux/iopoll.h>
> > #include <linux/kernel.h>
> > #include <linux/module.h>
> > #include <linux/of.h>
> > @@ -36,6 +37,7 @@
> > #define DEFAULT_TIMEOUT 60
> > #define MAX_TIMEOUT 128
> > #define WDOG_CLOCK_RATE 1000
> > +#define WDOG_WAIT_TIMEOUT 20
> >
> > static bool nowayout = WATCHDOG_NOWAYOUT;
> module_param(nowayout,
> > bool, 0000); @@ -48,17 +50,40 @@ struct imx7ulp_wdt_device {
> > struct clk *clk;
> > };
> >
> > -static void imx7ulp_wdt_enable(struct watchdog_device *wdog, bool
> > enable)
> > +static int imx7ulp_wdt_wait(void __iomem *base, u32 mask) {
> > + u32 val = readl(base + WDOG_CS);
> > +
> > + if (!(val & mask) && readl_poll_timeout_atomic(base + WDOG_CS, val,
> > + val & mask, 0,
> > + WDOG_WAIT_TIMEOUT))
> > + return -ETIMEDOUT;
> > +
> > + return 0;
> > +}
> > +
> > +static int imx7ulp_wdt_enable(struct watchdog_device *wdog, bool
> > +enable)
> > {
> > struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> >
> > u32 val = readl(wdt->base + WDOG_CS);
> > + int ret;
> >
> > + local_irq_disable();
> > writel(UNLOCK, wdt->base + WDOG_CNT);
> > + ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_ULK);
> > + if (ret)
> > + goto enable_out;
> > if (enable)
> > writel(val | WDOG_CS_EN, wdt->base + WDOG_CS);
> > else
> > writel(val & ~WDOG_CS_EN, wdt->base + WDOG_CS);
> > + imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> > +
> > +enable_out:
> > + local_irq_enable();
> > +
> > + return ret;
> > }
> >
> > static bool imx7ulp_wdt_is_enabled(void __iomem *base) @@ -79,17
> > +104,12 @@ static int imx7ulp_wdt_ping(struct watchdog_device *wdog)
> >
> > static int imx7ulp_wdt_start(struct watchdog_device *wdog) {
> > -
> > - imx7ulp_wdt_enable(wdog, true);
> > -
> > - return 0;
> > + return imx7ulp_wdt_enable(wdog, true);
> > }
> >
> > static int imx7ulp_wdt_stop(struct watchdog_device *wdog) {
> > - imx7ulp_wdt_enable(wdog, false);
> > -
> > - return 0;
> > + return imx7ulp_wdt_enable(wdog, false);
> > }
> >
> > static int imx7ulp_wdt_set_timeout(struct watchdog_device *wdog, @@
> > -97,22 +117,37 @@ static int imx7ulp_wdt_set_timeout(struct
> > watchdog_device *wdog, {
> > struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
> > u32 val = WDOG_CLOCK_RATE * timeout;
> > + int ret;
> >
> > + local_irq_disable();
> > writel(UNLOCK, wdt->base + WDOG_CNT);
> > + ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_ULK);
> > + if (ret)
> > + goto timeout_out;
> > writel(val, wdt->base + WDOG_TOVAL);
> > + imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> > +
> > +timeout_out:
> > + local_irq_enable();
> >
> > wdog->timeout = timeout;
>
> This needs to be moved up - the timeout did not get changed on error.
Ah, yes, will fix it in V4.
Thanks,
Anson
