linux-kernel - Re: [PATCH 4/7] watchdog: imx7ulp

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Message-ID: <20220823120656.GC203169@roeck-us.net>
Date:   Tue, 23 Aug 2022 05:06:56 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Alice Guo (OSS)" <alice.guo@....nxp.com>
Cc:     "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
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@...il.com> On Behalf Of Guenter Roeck
> > Sent: Monday, August 22, 2022 10:10 PM
> > To: Alice Guo (OSS) <alice.guo@....nxp.com>
> > Cc: wim@...ux-watchdog.org; shawnguo@...nel.org;
> > s.hauer@...gutronix.de; festevam@...il.com; kernel@...gutronix.de;
> > dl-linux-imx <linux-imx@....com>; linux-watchdog@...r.kernel.org;
> > linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org
> > 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@....com>
> > >
> > > 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

> Best Regards,
> Alice Guo
> 
> > > Signed-off-by: Ye Li <ye.li@....com>
> > > Signed-off-by: Alice Guo <alice.guo@....com>
> > > Reviewed-by: Jacky Bai <ping.bai@....com>
> > > Acked-by: Jason Liu <jason.hui.liu@....com>
> > > ---
> > >  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
> > >