[lm-sensors] [PATCH 6/7] hwmon: (w83795) Clear intrusion alarm

[lm-sensors] [PATCH 6/7] hwmon: (w83795) Clear intrusion alarm

[Jean Delvare]

When asked to clear the intrusion alarm, do so immediately. We have to
invalidate the cache to make sure the new status will be read. But we
also have to read from the status register once to clear the pending
alarm, as writing to CLR_CHS surprising won't clear it automatically.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 w83795.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/hwmon/w83795.c	2010-11-06 22:37:55.000000000 +0100
+++ b/drivers/hwmon/w83795.c	2010-11-06 22:40:03.000000000 +0100
@@ -755,6 +755,10 @@ store_chassis_clear(struct device *dev,
 	val = w83795_read(client, W83795_REG_CLR_CHASSIS);
 	val |= 0x80;
 	w83795_write(client, W83795_REG_CLR_CHASSIS, val);
+
+	/* Clear status and force cache refresh */
+	w83795_read(client, W83795_REG_ALARM(5));
+	data->valid = 0;
 	mutex_unlock(&data->update_lock);
 	return count;
 }

-- 
Jean Delvare

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Re: [lm-sensors] [PATCH 6/7] hwmon: (w83795) Clear intrusion alarm

[Guenter Roeck]

On Sun, Nov 07, 2010 at 10:47:19AM -0500, Jean Delvare wrote:
> When asked to clear the intrusion alarm, do so immediately. We have to
> invalidate the cache to make sure the new status will be read. But we
> also have to read from the status register once to clear the pending
> alarm, as writing to CLR_CHS surprising won't clear it automatically.
> 
> Signed-off-by: Jean Delvare <khali@linux-fr.org>
> ---
>  w83795.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> --- a/drivers/hwmon/w83795.c	2010-11-06 22:37:55.000000000 +0100
> +++ b/drivers/hwmon/w83795.c	2010-11-06 22:40:03.000000000 +0100
> @@ -755,6 +755,10 @@ store_chassis_clear(struct device *dev,
>  	val = w83795_read(client, W83795_REG_CLR_CHASSIS);
>  	val |= 0x80;
>  	w83795_write(client, W83795_REG_CLR_CHASSIS, val);
> +
> +	/* Clear status and force cache refresh */
> +	w83795_read(client, W83795_REG_ALARM(5));

Won't that clear other (possibly unreported) alarms as well ?

If that is not a problem, 
	Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>


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Re: [lm-sensors] [PATCH 6/7] hwmon: (w83795) Clear intrusion alarm

[Jean Delvare]

On Sun, 7 Nov 2010 09:24:59 -0800, Guenter Roeck wrote:
> On Sun, Nov 07, 2010 at 10:47:19AM -0500, Jean Delvare wrote:
> > When asked to clear the intrusion alarm, do so immediately. We have to
> > invalidate the cache to make sure the new status will be read. But we
> > also have to read from the status register once to clear the pending
> > alarm, as writing to CLR_CHS surprising won't clear it automatically.
> > 
> > Signed-off-by: Jean Delvare <khali@linux-fr.org>
> > ---
> >  w83795.c |    4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > --- a/drivers/hwmon/w83795.c	2010-11-06 22:37:55.000000000 +0100
> > +++ b/drivers/hwmon/w83795.c	2010-11-06 22:40:03.000000000 +0100
> > @@ -755,6 +755,10 @@ store_chassis_clear(struct device *dev,
> >  	val = w83795_read(client, W83795_REG_CLR_CHASSIS);
> >  	val |= 0x80;
> >  	w83795_write(client, W83795_REG_CLR_CHASSIS, val);
> > +
> > +	/* Clear status and force cache refresh */
> > +	w83795_read(client, W83795_REG_ALARM(5));
> 
> Won't that clear other (possibly unreported) alarms as well ?

It will clear the interrupt bit for other sources in that register,
yes. But the update function does exactly this already, so this is
nothing new. I don't think it will have any effect on the real-time
register, but I can't check it, because the other sources in that
register are fan9 to fan14, which do not exist on my system.

If I get any report of a user with more than 8 fans connected to a
W83795G/ADG device, I'll check the exact behavior. But I think the
current code is and will stay acceptable regardless, because clearing
the chassis intrusion status is such a rare event.

> 
> If that is not a problem, 
> 	Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
> 


-- 
Jean Delvare

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