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From: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Philipp Zabel <p.zabel@pengutronix.de>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Wim Van Sebroeck <wim@iguana.be>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	Simon Horman <horms@verge.net.au>,
	Magnus Damm <magnus.damm@gmail.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
	"linux-renesas-soc@vger.kernel.org"
	<linux-renesas-soc@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>linux-
Subject: RE: [RFC 22/37] watchdog: renesas_wdt: Add restart support
Date: Fri, 26 Jan 2018 17:50:16 +0000	[thread overview]
Message-ID: <TY1PR06MB0895CE80DD4121A7EB6B3B05C0E00@TY1PR06MB0895.apcprd06.prod.outlook.com> (raw)
In-Reply-To: <20180126171418.GA16194@roeck-us.net>

Hello Guenter,

thank you for your feedback.

> Subject: Re: [RFC 22/37] watchdog: renesas_wdt: Add restart support
>
> On Thu, Jan 25, 2018 at 06:02:56PM +0000, Fabrizio Castro wrote:
> > This commit extends the driver to add restart support by implementing
> > the restart callback to trigger the watchdog as quickly as possible.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> > Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
> > ---
> >  drivers/watchdog/renesas_wdt.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
> > index 831ef83..120ddac 100644
> > --- a/drivers/watchdog/renesas_wdt.c
> > +++ b/drivers/watchdog/renesas_wdt.c
> > @@ -107,6 +107,24 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
> >  return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
> >  }
> >
> > +static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
> > +void *data)
> > +{
> > +struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
> > +
> > +pm_runtime_get_sync(wdev->parent);
> > +
> > +rwdt_write(priv, 0x00, RWTCSRB);
> > +rwdt_write(priv, 0x00, RWTCSRA);
> > +rwdt_write(priv, 0xffff, RWTCNT);
> > +
> > +while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
> > +cpu_relax();
>
> Can this get stuck forever or should there be a timeout ?

This won't get stuck forever, the particular bit we are checking marks the period of time writing to register RWTCNT is prohibited due to synchronization from the previous write. It gets cleared eventually (quite quickly). Also, we use exactly the same logic for the "start" callback.

Best regards,
Fabrizio

>
> Guenter
>
> > +
> > +rwdt_write(priv, 0x80, RWTCSRA);
> > +return 0;
> > +}
> > +
> >  static const struct watchdog_info rwdt_ident = {
> >  .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
> >  .identity = "Renesas WDT Watchdog",
> > @@ -118,6 +136,7 @@ static const struct watchdog_ops rwdt_ops = {
> >  .stop = rwdt_stop,
> >  .ping = rwdt_init_timeout,
> >  .get_timeleft = rwdt_get_timeleft,
> > +.restart = rwdt_restart,
> >  };
> >
> >  static int rwdt_probe(struct platform_device *pdev)
> > --
> > 2.7.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html



Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.

  reply	other threads:[~2018-01-26 17:50 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-25 18:02 [RFC 00/37] Fix watchdog on Renesas R-Car Gen2 and RZ/G1 Fabrizio Castro
2018-01-25 18:02 ` [RFC 01/37] ARM: shmobile: Add watchdog support Fabrizio Castro
     [not found]   ` <1516903391-30467-2-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26  9:46     ` Geert Uytterhoeven
     [not found]       ` <CAMuHMdWVvMJR5NHMFn6zx39jw2XdP5nteU3actUcen0dmoT-LQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-01-26  9:49         ` Geert Uytterhoeven
2018-01-26 11:52         ` Fabrizio Castro
2018-01-26 12:10           ` Geert Uytterhoeven
2018-01-26 13:44             ` Fabrizio Castro
2018-01-26 16:08           ` [RFC v2 " Fabrizio Castro
2018-01-26 16:08             ` [RFC v2 23/37] ARM: shmobile: rcar-gen2: Export shmobile_set_wdt_clock_status function Fabrizio Castro
     [not found]             ` <1516982937-29245-1-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 16:16               ` [RFC v2 01/37] ARM: shmobile: Add watchdog support Fabrizio Castro
2018-01-25 18:02 ` [RFC 02/37] ARM: dts: r8a7743: Adjust SMP routine size Fabrizio Castro
     [not found]   ` <1516903391-30467-3-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26  9:52     ` Geert Uytterhoeven
2018-01-25 18:02 ` [RFC 05/37] ARM: dts: r8a7791: " Fabrizio Castro
2018-01-26  9:53   ` Geert Uytterhoeven
2018-01-25 18:02 ` [RFC 07/37] ARM: dts: r8a7793: " Fabrizio Castro
     [not found]   ` <1516903391-30467-8-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26  9:53     ` Geert Uytterhoeven
2018-01-25 18:02 ` [RFC 08/37] ARM: dts: r8a7794: " Fabrizio Castro
2018-01-26  9:54   ` Geert Uytterhoeven
2018-01-25 18:02 ` [RFC 09/37] soc: renesas: rcar-rst: Add generic compatible strings Fabrizio Castro
     [not found]   ` <1516903391-30467-10-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:00     ` Geert Uytterhoeven
2018-01-25 18:02 ` [RFC 10/37] soc: renesas: rcar-rst: Enable watchdog as reset trigger for Gen2 Fabrizio Castro
     [not found]   ` <1516903391-30467-11-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26  8:30     ` Sergei Shtylyov
     [not found]       ` <e1670c79-2fef-b45b-4688-a6ba8ebd8c24-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org>
2018-01-26 16:59         ` Fabrizio Castro
2018-01-26 10:05     ` Geert Uytterhoeven
2018-01-25 18:02 ` [RFC 12/37] ARM: dts: r8a7743: Use fallback rst compatible string Fabrizio Castro
2018-01-25 18:02 ` [RFC 15/37] ARM: dts: r8a7791: " Fabrizio Castro
2018-01-25 18:02 ` [RFC 20/37] arm64: dts: renesas: r8a77995: " Fabrizio Castro
2018-01-25 18:02 ` [RFC 21/37] dt-bindings: watchdog: renesas-wdt: Add R-Car Gen2 support Fabrizio Castro
     [not found]   ` <1516903391-30467-22-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:10     ` Geert Uytterhoeven
     [not found] ` <1516903391-30467-1-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-25 18:02   ` [RFC 03/37] ARM: dts: r8a7745: Adjust SMP routine size Fabrizio Castro
2018-01-26  9:52     ` Geert Uytterhoeven
2018-01-25 18:02   ` [RFC 04/37] ARM: dts: r8a7790: " Fabrizio Castro
2018-01-26  9:53     ` Geert Uytterhoeven
2018-01-25 18:02   ` [RFC 06/37] ARM: dts: r8a7792: " Fabrizio Castro
2018-01-26  9:53     ` Geert Uytterhoeven
2018-01-25 18:02   ` [RFC 11/37] soc: renesas: rcar-rst: Document generic compatible strings Fabrizio Castro
2018-01-26 10:06     ` Geert Uytterhoeven
2018-01-25 18:02   ` [RFC 13/37] ARM: dts: r8a7745: Use fallback rst compatible string Fabrizio Castro
2018-01-25 18:02   ` [RFC 14/37] ARM: dts: r8a7790: " Fabrizio Castro
2018-01-25 18:02   ` [RFC 16/37] ARM: dts: r8a7794: " Fabrizio Castro
2018-01-25 18:02   ` [RFC 17/37] arm64: dts: renesas: r8a7795: " Fabrizio Castro
2018-01-25 18:02   ` [RFC 18/37] arm64: dts: renesas: r8a7796: " Fabrizio Castro
2018-01-25 18:02   ` [RFC 19/37] arm64: dts: renesas: r8a77970: " Fabrizio Castro
2018-01-25 18:02   ` [RFC 22/37] watchdog: renesas_wdt: Add restart support Fabrizio Castro
2018-01-26 10:11     ` Geert Uytterhoeven
2018-01-26 17:14     ` Guenter Roeck
2018-01-26 17:50       ` Fabrizio Castro [this message]
2018-01-25 18:02   ` [RFC 23/37] ARM: shmobile: rcar-gen2: Export shmobile_set_wdt_clock_status function Fabrizio Castro
     [not found]     ` <1516903391-30467-24-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:16       ` Geert Uytterhoeven
2018-01-25 18:03   ` [RFC 29/37] clk: renesas: r8a7791/r8a7793: Add rwdt clock Fabrizio Castro
     [not found]     ` <1516903391-30467-30-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:25       ` Geert Uytterhoeven
2018-01-25 18:03   ` [RFC 33/37] ARM: dts: r8a7790: Add watchdog support to SoC dtsi Fabrizio Castro
2018-01-26 10:30     ` Geert Uytterhoeven
2018-01-25 18:03   ` [RFC 35/37] ARM: dts: r8a7794: " Fabrizio Castro
     [not found]     ` <1516903391-30467-36-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:31       ` Geert Uytterhoeven
2018-01-25 18:03   ` [RFC 37/37] ARM: dts: iwg22m: Add watchdog support to SoM dtsi Fabrizio Castro
     [not found]     ` <1516903391-30467-38-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:32       ` Geert Uytterhoeven
2018-01-25 18:02 ` [RFC 24/37] watchdog: renesas_wdt_gen2: Add Gen2 specific driver Fabrizio Castro
2018-01-26 10:22   ` Geert Uytterhoeven
     [not found]   ` <1516903391-30467-25-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 17:28     ` Guenter Roeck
     [not found]       ` <20180126172835.GB16194-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
2018-01-26 18:00         ` Fabrizio Castro
2018-01-25 18:02 ` [RFC 25/37] ARM: shmobile: defconfig: Enable RENESAS_WDT_GEN2 Fabrizio Castro
2018-01-25 18:03 ` [RFC 26/37] clk: renesas: r8a7743: Add rwdt clock Fabrizio Castro
2018-01-26 10:33   ` Geert Uytterhoeven
2018-01-25 18:03 ` [RFC 27/37] clk: renesas: r8a7745: " Fabrizio Castro
2018-01-26 10:24   ` Geert Uytterhoeven
2018-01-25 18:03 ` [RFC 28/37] clk: renesas: r8a7790: " Fabrizio Castro
     [not found]   ` <1516903391-30467-29-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:25     ` Geert Uytterhoeven
2018-01-25 18:03 ` [RFC 30/37] clk: renesas: r8a7794: " Fabrizio Castro
     [not found]   ` <1516903391-30467-31-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:25     ` Geert Uytterhoeven
2018-01-25 18:03 ` [RFC 31/37] ARM: dts: r8a7743: Add watchdog support to SoC dtsi Fabrizio Castro
2018-01-26 10:27   ` Geert Uytterhoeven
2018-01-25 18:03 ` [RFC 32/37] ARM: dts: r8a7745: " Fabrizio Castro
2018-01-26 10:28   ` Geert Uytterhoeven
2018-01-25 18:03 ` [RFC 34/37] ARM: dts: r8a7791: " Fabrizio Castro
     [not found]   ` <1516903391-30467-35-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:30     ` Geert Uytterhoeven
2018-01-25 18:03 ` [RFC 36/37] ARM: dts: iwg20m: Add watchdog support to SoM dtsi Fabrizio Castro
     [not found]   ` <1516903391-30467-37-git-send-email-fabrizio.castro-kTT6dE0pTRh9uiUsa/gSgQ@public.gmane.org>
2018-01-26 10:32     ` Geert Uytterhoeven

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