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From: Nicolin Chen <nicoleotsuka@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-hwmon@vger.kernel.org
Subject: Re: ABI for these two registers?
Date: Thu, 12 Sep 2019 17:12:38 -0700
Message-ID: <20190913001237.GA31111@Asurada-Nvidia.nvidia.com> (raw)
In-Reply-To: <20190912224528.GA24937@Asurada-Nvidia.nvidia.com>

On Thu, Sep 12, 2019 at 03:45:29PM -0700, Nicolin Chen wrote:
> On Thu, Sep 12, 2019 at 03:09:47PM -0700, Guenter Roeck wrote:
> > On Thu, Sep 12, 2019 at 02:09:58PM -0700, Nicolin Chen wrote:
> > > Hello Guenter,
> > > 
> > > On Thu, Sep 12, 2019 at 11:32:18AM -0700, Guenter Roeck wrote:
> > > > On Wed, Sep 11, 2019 at 05:28:14PM -0700, Nicolin Chen wrote:
> > > > > Hello Guenter,
> > > > > 
> > > > > Datasheet: http://www.ti.com/lit/ds/symlink/ina3221.pdf
> > > > > (At page 32, chapter 8.6.2.14 and 8.6.2.15)
> > > > > 
> > > > > I have two registers that I need to expose to user space:
> > > > > 	Shunt-Voltage-Sum and Shunt-Voltage-Limit registers
> > > > > 
> > > > > Right now in[123]_input of INA3221 are for voltage channels
> > > > > while in[456]_input are for Shunt voltage channels.
> > > > > 
> > > > > So can I just use in7_input and in7_crit for them?
> > > > > 
> > > > Doesn't Shunt-Voltage-Limit apply to in[456]_input ?
> > > > If so, the limit should be attached to those.
> > > 
> > > The initial patch of ina3221 driver applied Shunt-Voltage-Limits,
> > > being named as "Critical Alert Limit Registers" in the datasheet,
> > > to curr[123]_crit, corresponding to curr[123] and in[456]_input.
> > > 
> > > And this Shunt-Voltage-Limit-Sum is more related to the reading
> > > from Shunt-Voltage-Sum, which we just agreed it to be in7_input.
> > > 
> > You didn't say Shunt-Voltage-Limit-Sum earlier. You said
> 
> Ah....right...it's my fault. Sorry.
> 
> > Shunt-Voltage-Limit. I would agree that Shunt-Voltage-Limit-Sum is
> > associated with Shunt-Voltage-Sum, but, again, that is not what you
> > said earlier. Confused :-(
> 
> So, those two should be in7_input and in7_crit?

And a couple of more questions upon it:

1) There are 3 control bits for the summation of this
   shunt-voltage-sum register to enable corresponding
   input channels. But in7_enable only allows users to
   en/disable all three channels at the same time. So
   how should I attach three enable bits using ABI?
   Or should I create a device-specific sysfs node?

2) We have a requirement of providing current-sum and
   current-limit-sum nodes, for use cases where those
   enabled channels use same value shunt resistors.
   It's similar to provide curr[1-3]_crit by dividing
   shunt[123]_resistor from in[456]_input. So could I
   deploy curr4_input and curr4_crit nodes for this
   requirement?

Thank you!

      reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-12  0:28 Nicolin Chen
2019-09-12 18:32 ` Guenter Roeck
2019-09-12 21:09   ` Nicolin Chen
2019-09-12 22:09     ` Guenter Roeck
2019-09-12 22:45       ` Nicolin Chen
2019-09-13  0:12         ` Nicolin Chen [this message]

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