linux-kernel - RE: [PATCH] watchdog: rzg2l_wdt: Issue a reset before we put the PM clocks

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Message-ID: <OS0PR01MB5922E8CB8DB680347BEB997C86059@OS0PR01MB5922.jpnprd01.prod.outlook.com>
Date:   Mon, 14 Nov 2022 19:53:02 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
CC:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: RE: [PATCH] watchdog: rzg2l_wdt: Issue a reset before we put the PM
 clocks



> -----Original Message-----
> From: Lad, Prabhakar <prabhakar.csengg@...il.com>
> Sent: 14 November 2022 19:46
> To: Biju Das <biju.das.jz@...renesas.com>
> Cc: Geert Uytterhoeven <geert+renesas@...der.be>; Wim Van Sebroeck
> <wim@...ux-watchdog.org>; Guenter Roeck <linux@...ck-us.net>; Philipp
> Zabel <p.zabel@...gutronix.de>; linux-watchdog@...r.kernel.org; linux-
> kernel@...r.kernel.org; linux-renesas-soc@...r.kernel.org; Fabrizio
> Castro <fabrizio.castro.jz@...esas.com>; Prabhakar Mahadev Lad
> <prabhakar.mahadev-lad.rj@...renesas.com>
> Subject: Re: [PATCH] watchdog: rzg2l_wdt: Issue a reset before we put
> the PM clocks
> 
> HI Biju,
> 
> Thank you for the review.
> 
> On Mon, Nov 14, 2022 at 6:42 PM Biju Das <biju.das.jz@...renesas.com>
> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Prabhakar <prabhakar.csengg@...il.com>
> > > Sent: 14 November 2022 18:09
> > > To: Geert Uytterhoeven <geert+renesas@...der.be>; Wim Van Sebroeck
> > > <wim@...ux-watchdog.org>; Guenter Roeck <linux@...ck-us.net>;
> > > Philipp Zabel <p.zabel@...gutronix.de>;
> > > linux-watchdog@...r.kernel.org
> > > Cc: linux-kernel@...r.kernel.org; linux-renesas-
> soc@...r.kernel.org;
> > > Prabhakar <prabhakar.csengg@...il.com>; Biju Das
> > > <biju.das.jz@...renesas.com>; Fabrizio Castro
> > > <fabrizio.castro.jz@...esas.com>; Prabhakar Mahadev Lad
> > > <prabhakar.mahadev- lad.rj@...renesas.com>
> > > Subject: [PATCH] watchdog: rzg2l_wdt: Issue a reset before we put
> > > the PM clocks
> > >
> > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > >
> > > On RZ/Five SoC it was observed that setting timeout (to say 1 sec)
> > > wouldn't reset the system. To fix this we make sure we issue a
> reset
> > > before putting the PM clocks to make sure the registers have been
> cleared.
> > >
> > > While at it re-used rzg2l_wdt_stop() in rzg2l_wdt_set_timeout() as
> > > we were calling the same functions here.
> > >
> > > Signed-off-by: Lad Prabhakar
> > > <prabhakar.mahadev-lad.rj@...renesas.com>
> > > ---
> > > Note,
> > > - This patch has been tested on RZ/G2L, RZ/V2M and RZ/Five.
> > > - My initial investigation showed adding the delay after
> > > pm_runtime_get_sync()
> > >   also fixed this issue.
> > > - Do I need add the fixes tag ? what should be the operation PUT-
> > > >RESET/RESET->PUT?
> >
> > It looks like timing issue, None of the previous devices are
> affected by this.
> >
> yep.
> 
> > >   in case we need the tag is:
> > >   Fixes: 4055ee81009e6 ("watchdog: rzg2l_wdt: Add set_timeout
> > > callback")
> > > ---
> > >  drivers/watchdog/rzg2l_wdt.c | 7 ++-----
> > >  1 file changed, 2 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/watchdog/rzg2l_wdt.c
> > > b/drivers/watchdog/rzg2l_wdt.c index 00438ceed17a..d1271cc7750f
> > > 100644
> > > --- a/drivers/watchdog/rzg2l_wdt.c
> > > +++ b/drivers/watchdog/rzg2l_wdt.c
> > > @@ -115,16 +115,14 @@ static int rzg2l_wdt_stop(struct
> > > watchdog_device *wdev) {
> > >       struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > >
> > > -     pm_runtime_put(wdev->parent);
> > >       reset_control_reset(priv->rstc);
> > > +     pm_runtime_put(wdev->parent);
> > >
> > >       return 0;
> > >  }
> > >
> > >  static int rzg2l_wdt_set_timeout(struct watchdog_device *wdev,
> > > unsigned int
> > > timeout)  {
> > > -     struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> > > -
> > >       wdev->timeout = timeout;
> > >
> > >       /*
> > > @@ -132,8 +130,7 @@ static int rzg2l_wdt_set_timeout(struct
> > > watchdog_device *wdev, unsigned int time
> > >        * register so that it is updated with new timeout values.
> > >        */
> >
> >
> > Maybe update the comment above with new code change.
> >
>     /*
>      * If the watchdog is active, reset the module for updating the
> WDTSET
>      * register so that it is updated with new timeout values.
>      */
> 
> The above existing comment holds good with this code change. If you
> prefer something else please let me know I'll update it accordingly.

Maybe mention, The resetting of the module is done in wdt_stop function.

Cheers,
Biju