linux-kernel - Re: [PATCH v3 2/4] hwmon: (lm90) use macro defines for the status bit

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Date:	Wed, 30 Oct 2013 09:56:44 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Jean Delvare <khali@...ux-fr.org>
Cc:	Wei Ni <wni@...dia.com>, thierry.reding@...il.com,
	lm-sensors@...sensors.org, linux-kernel@...r.kernel.org,
	linux-tegra@...r.kernel.org
Subject: Re: [PATCH v3 2/4] hwmon: (lm90) use macro defines for the status bit

On Wed, Oct 30, 2013 at 04:33:26PM +0100, Jean Delvare wrote:
> Hi Guenter,
> 
> On Mon, 15 Jul 2013 10:33:22 -0700, Guenter Roeck wrote:
> > On Mon, Jul 15, 2013 at 06:57:27PM +0200, Jean Delvare wrote:
> > > Unrelated to this patch, but Guenter, I am worried about the MAX6696
> > > handling here. I realize that I am the one who accepted your code, but
> > > now it looks wrong. Specifically:
> > > * We check for (status2 & 0xfe) i.e. 7 alarm bits, but the code below
> > >   only reports 2 alarms bits. So if any of the 5 other alarm bits in
> > >   STATUS2 are, we may return true (chip is tripped) but not print the
> > >   cause.

Agreed, that doesn't make much sense, especially since we already check
for R1OT1 and display a message if it is set. I'll add checks for the other
bits.

> > > * At least bits 1 and 2 of STATUS 2 fit totally fine in the driver as
> > >   it currently exists, so I can't think of any reason for not handling
> > >   them. Why are we not? Ideally we should print a message for every
> > >   alarm bit so that we never return "true" without printing a message.
> > >   Even though OT2 limits aren't handled by the driver...

They actually are, through MAX6659_REG_R_REMOTE_EMERG and LM90_HAVE_EMERGENCY.

> > > * If you think this piece of code shouldn't deal with OT/THERM limits
> > >   because they do not trigger an SMBus alarm, this can be discussed,

Yes, that was the logic. Presumably OT1 and OT2 are separate interrupts
(if connected to interrupt pins) and would have to be handled separately.

> > >   but all chips should be handled the same in this respect then.

Agreed.

> > > * Why in the first place is max6696's data->alert_alarms set to 0x187c
> > >   and not 0x1c7c? Including 1OPEN but not 2OPEN makes no sense.

Oversight. 2OPEN does trigger ALERT, so the bit should be set.

I'll send a patch in a minute.

Guenter
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