wdt_aspeed: Fix behaviour of control register

[PATCH 2/2] watchdog: aspeed: Fix sequential control writes

Posted by Andrew Jeffery 4 years, 7 months ago

The logic in the handling for the control register required toggling the
enable state for writes to stick. Rework the condition chain to allow
sequential writes that do not update the enable state.

Fixes: 854123bf8d4b ("wdt: Add Aspeed watchdog device model")
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
 hw/watchdog/wdt_aspeed.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/watchdog/wdt_aspeed.c b/hw/watchdog/wdt_aspeed.c
index faa3d35fdf21..69c37af9a6e9 100644
--- a/hw/watchdog/wdt_aspeed.c
+++ b/hw/watchdog/wdt_aspeed.c
@@ -166,6 +166,8 @@ static void aspeed_wdt_write(void *opaque, hwaddr offset, uint64_t data,
         } else if (!enable && aspeed_wdt_is_enabled(s)) {
             s->regs[WDT_CTRL] = data;
             timer_del(s->timer);
+        } else {
+            s->regs[WDT_CTRL] = data;
         }
         break;
     case WDT_RESET_WIDTH:
-- 
2.30.2

Re: [PATCH 2/2] watchdog: aspeed: Fix sequential control writes

Posted by Philippe Mathieu-Daudé 4 years, 7 months ago

On 7/9/21 7:31 AM, Andrew Jeffery wrote:
> The logic in the handling for the control register required toggling the
> enable state for writes to stick. Rework the condition chain to allow
> sequential writes that do not update the enable state.
> 
> Fixes: 854123bf8d4b ("wdt: Add Aspeed watchdog device model")
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
>  hw/watchdog/wdt_aspeed.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/hw/watchdog/wdt_aspeed.c b/hw/watchdog/wdt_aspeed.c
> index faa3d35fdf21..69c37af9a6e9 100644
> --- a/hw/watchdog/wdt_aspeed.c
> +++ b/hw/watchdog/wdt_aspeed.c
> @@ -166,6 +166,8 @@ static void aspeed_wdt_write(void *opaque, hwaddr offset, uint64_t data,
>          } else if (!enable && aspeed_wdt_is_enabled(s)) {
>              s->regs[WDT_CTRL] = data;
>              timer_del(s->timer);
> +        } else {
> +            s->regs[WDT_CTRL] = data;

What about simplifying by moving here:

               if (!enable && aspeed_wdt_is_enabled(s)) {
                   timer_del(s->timer);
               }

>          }
>          break;
>      case WDT_RESET_WIDTH:
>

Re: [PATCH 2/2] watchdog: aspeed: Fix sequential control writes

Posted by Andrew Jeffery 4 years, 7 months ago


On Fri, 9 Jul 2021, at 16:59, Philippe Mathieu-Daudé wrote:
> On 7/9/21 7:31 AM, Andrew Jeffery wrote:
> > The logic in the handling for the control register required toggling the
> > enable state for writes to stick. Rework the condition chain to allow
> > sequential writes that do not update the enable state.
> > 
> > Fixes: 854123bf8d4b ("wdt: Add Aspeed watchdog device model")
> > Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> > ---
> >  hw/watchdog/wdt_aspeed.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/hw/watchdog/wdt_aspeed.c b/hw/watchdog/wdt_aspeed.c
> > index faa3d35fdf21..69c37af9a6e9 100644
> > --- a/hw/watchdog/wdt_aspeed.c
> > +++ b/hw/watchdog/wdt_aspeed.c
> > @@ -166,6 +166,8 @@ static void aspeed_wdt_write(void *opaque, hwaddr offset, uint64_t data,
> >          } else if (!enable && aspeed_wdt_is_enabled(s)) {
> >              s->regs[WDT_CTRL] = data;
> >              timer_del(s->timer);
> > +        } else {
> > +            s->regs[WDT_CTRL] = data;
> 
> What about simplifying by moving here:
> 
>                if (!enable && aspeed_wdt_is_enabled(s)) {
>                    timer_del(s->timer);
>                }
> 

I don't think that works, as aspeed_wdt_is_enabled() tests the value of 
s->regs[WDT_CTRL]. If you set it before you test then you end up in the 
wrong state.

Andrew

Re: [PATCH 2/2] watchdog: aspeed: Fix sequential control writes

Posted by Cédric Le Goater 4 years, 6 months ago

On 7/9/21 7:31 AM, Andrew Jeffery wrote:
> The logic in the handling for the control register required toggling the
> enable state for writes to stick. Rework the condition chain to allow
> sequential writes that do not update the enable state.
> 
> Fixes: 854123bf8d4b ("wdt: Add Aspeed watchdog device model")
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

> ---
>  hw/watchdog/wdt_aspeed.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/hw/watchdog/wdt_aspeed.c b/hw/watchdog/wdt_aspeed.c
> index faa3d35fdf21..69c37af9a6e9 100644
> --- a/hw/watchdog/wdt_aspeed.c
> +++ b/hw/watchdog/wdt_aspeed.c
> @@ -166,6 +166,8 @@ static void aspeed_wdt_write(void *opaque, hwaddr offset, uint64_t data,
>          } else if (!enable && aspeed_wdt_is_enabled(s)) {
>              s->regs[WDT_CTRL] = data;
>              timer_del(s->timer);
> +        } else {
> +            s->regs[WDT_CTRL] = data;
>          }
>          break;
>      case WDT_RESET_WIDTH:
>