RE: [PATCH 4/7] watchdog: imx7ulp_wdt: Fix RCS timeout issue

[Alice Guo (OSS)]

> -----Original Message-----
> From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck
> Sent: Tuesday, August 23, 2022 8:07 PM
> To: Alice Guo (OSS) <alice.guo@xxxxxxxxxxx>
> Cc: wim@xxxxxxxxxxxxxxxxxx; shawnguo@xxxxxxxxxx;
> s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; kernel@xxxxxxxxxxxxxx;
> dl-linux-imx <linux-imx@xxxxxxx>; linux-watchdog@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH 4/7] watchdog: imx7ulp_wdt: Fix RCS timeout issue
> 
> On Tue, Aug 23, 2022 at 05:59:11AM +0000, Alice Guo (OSS) wrote:
> >
> >
> > > -----Original Message-----
> > > From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck
> > > Sent: Monday, August 22, 2022 10:10 PM
> > > To: Alice Guo (OSS) <alice.guo@xxxxxxxxxxx>
> > > Cc: wim@xxxxxxxxxxxxxxxxxx; shawnguo@xxxxxxxxxx;
> > > s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; kernel@xxxxxxxxxxxxxx;
> > > dl-linux-imx <linux-imx@xxxxxxx>; linux-watchdog@xxxxxxxxxxxxxxx;
> > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > > Subject: Re: [PATCH 4/7] watchdog: imx7ulp_wdt: Fix RCS timeout
> > > issue
> > >
> > > On Tue, Aug 16, 2022 at 12:36:40PM +0800, Alice Guo (OSS) wrote:
> > > > From: Ye Li <ye.li@xxxxxxx>
> > > >
> > > > According to measure on i.MX7ULP and i.MX8ULP, the RCS done needs
> > > > about 3400us and 6700us respectively. So current 20us timeout is
> > > > not enough. When reconfiguring is on-going, unlock and configure
> > > > CS will lead to unknown result.
> > > >
> > > > Increase the wait timeout value to 10ms and check the return value
> > > > of RCS wait to fix the issue
> > > >
> > >
> > > You'll have to find a better solution. An active (non-sleep) wait of
> > > 10 ms is unacceptable.
> > >
> > > Guenter
> >
> > Hi Guenter,
> >
> > Sorry. I think this patch should be merged with " watchdog: imx7ulp_wdt:
> Handle wdog reconfigure failure", but I didn't merge them. I will send v2.
> >
> 
> That doesn't change the fact that a 10 ms hot wait is unacceptable.
> 
> Thanks,
> Guenter

Hi Guenter,

I plan to use readl_poll_timeout to wait for RCS(Reconfiguration Success). I think the sleep_us of readl_poll_timeout can be used to avoid a 10 ms hot wait.

Best Regards,
Alice Guo

> > Best Regards,
> > Alice Guo
> >
> > > > Signed-off-by: Ye Li <ye.li@xxxxxxx>
> > > > Signed-off-by: Alice Guo <alice.guo@xxxxxxx>
> > > > Reviewed-by: Jacky Bai <ping.bai@xxxxxxx>
> > > > Acked-by: Jason Liu <jason.hui.liu@xxxxxxx>
> > > > ---
> > > >  drivers/watchdog/imx7ulp_wdt.c | 8 +++++---
> > > >  1 file changed, 5 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/watchdog/imx7ulp_wdt.c
> > > > b/drivers/watchdog/imx7ulp_wdt.c index a0f6b8cea78f..12715c248688
> > > > 100644
> > > > --- a/drivers/watchdog/imx7ulp_wdt.c
> > > > +++ b/drivers/watchdog/imx7ulp_wdt.c
> > > > @@ -39,7 +39,7 @@
> > > >  #define DEFAULT_TIMEOUT	60
> > > >  #define MAX_TIMEOUT	128
> > > >  #define WDOG_CLOCK_RATE	1000
> > > > -#define WDOG_WAIT_TIMEOUT	20
> > > > +#define WDOG_WAIT_TIMEOUT	10000
> > > >
> > > >  static bool nowayout = WATCHDOG_NOWAYOUT;
> > > module_param(nowayout,
> > > > bool, 0000); @@ -80,7 +80,7 @@ static int
> > > > imx7ulp_wdt_enable(struct watchdog_device *wdog, bool 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);
> > > > +	ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> > > >
> > > >  enable_out:
> > > >  	local_irq_enable();
> > > > @@ -127,7 +127,9 @@ static int imx7ulp_wdt_set_timeout(struct
> > > watchdog_device *wdog,
> > > >  	if (ret)
> > > >  		goto timeout_out;
> > > >  	writel(val, wdt->base + WDOG_TOVAL);
> > > > -	imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> > > > +	ret = imx7ulp_wdt_wait(wdt->base, WDOG_CS_RCS);
> > > > +	if (ret)
> > > > +		goto timeout_out;
> > > >
> > > >  	wdog->timeout = timeout;
> > > >
> > > > --
> > > > 2.17.1
> > > >