Re: [PATCH] watchdog: rzg2l_wdt: Issue a reset before we put the PM clocks

[Lad, Prabhakar]

On Mon, Nov 14, 2022 at 7:53 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
>
>
>
> > -----Original Message-----
> > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > Sent: 14 November 2022 19:46
> > To: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>; Wim Van Sebroeck
> > <wim@xxxxxxxxxxxxxxxxxx>; Guenter Roeck <linux@xxxxxxxxxxxx>; Philipp
> > Zabel <p.zabel@xxxxxxxxxxxxxx>; linux-watchdog@xxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; linux-renesas-soc@xxxxxxxxxxxxxxx; Fabrizio
> > Castro <fabrizio.castro.jz@xxxxxxxxxxx>; Prabhakar Mahadev Lad
> > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > 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@xxxxxxxxxxxxxx>
> > wrote:
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > > Sent: 14 November 2022 18:09
> > > > To: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>; Wim Van Sebroeck
> > > > <wim@xxxxxxxxxxxxxxxxxx>; Guenter Roeck <linux@xxxxxxxxxxxx>;
> > > > Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>;
> > > > linux-watchdog@xxxxxxxxxxxxxxx
> > > > Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-renesas-
> > soc@xxxxxxxxxxxxxxx;
> > > > Prabhakar <prabhakar.csengg@xxxxxxxxx>; Biju Das
> > > > <biju.das.jz@xxxxxxxxxxxxxx>; Fabrizio Castro
> > > > <fabrizio.castro.jz@xxxxxxxxxxx>; Prabhakar Mahadev Lad
> > > > <prabhakar.mahadev- lad.rj@xxxxxxxxxxxxxx>
> > > > Subject: [PATCH] watchdog: rzg2l_wdt: Issue a reset before we put
> > > > the PM clocks
> > > >
> > > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > > >
> > > > 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@xxxxxxxxxxxxxx>
> > > > ---
> > > > 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.
>
    /*
     * If the watchdog is active, reset the module for updating the WDTSET
     * register by calling rzg2l_wdt_stop() (which internally calls
reset_control_reset() and pm_runtime_put()
     * so that it is updated with new timeout values.
     */

Does the above look good?

Cheers,
Prabhakar