linux-kernel - Re: [PATCH v3 1/5] Documentation: add DT bindings for ARM SCPI sensors

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <1442334689.4040.68.camel@linaro.org>
Date:	Tue, 15 Sep 2015 17:31:29 +0100
From:	"Jon Medhurst (Tixy)" <tixy@...aro.org>
To:	Punit Agrawal <punit.agrawal@....com>
Cc:	Mark Rutland <mark.rutland@....com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Liviu Dudau <Liviu.Dudau@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	"edubezval@...il.com" <edubezval@...il.com>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"linux@...ck-us.net" <linux@...ck-us.net>,
	Sudeep Holla <Sudeep.Holla@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 1/5] Documentation: add DT bindings for ARM SCPI
 sensors

On Tue, 2015-09-15 at 17:04 +0100, Punit Agrawal wrote:
> "Jon Medhurst (Tixy)" <tixy@...aro.org> writes:
> 
> > On Tue, 2015-09-15 at 10:37 +0100, Punit Agrawal wrote:
> >> "Jon Medhurst (Tixy)" <tixy@...aro.org> writes:
> >> 
> >> > On Mon, 2015-09-14 at 15:38 +0100, Punit Agrawal wrote:
> >> >> Mark Rutland <mark.rutland@....com> writes:
> >> >> 
> > [...]
> >> >> The way the SCP interface is defined, the sensor identifiers are
> >> >> contiguous,
> >> >
> >> > Is there any documentation other than DUI0922A? [1] From what I can seen
> >> > that just says it's a 16-bit value and doesn't put any particular
> >> > constraints on its value.
> >> 
> >> Although not explicitly stated, if you look at the Get Sensor Capability
> >> [2] and Get Sensor Info [3] commands you can indirectly infer that the
> >> Sensor IDs are contiguous.
> >
> > I personally wouldn't even indirectly infer they are contiguous from
> > what the document says. If I were implementing the firmware I would feel
> > quite in my rights to, for example, use the top 8 bits of the ID for a
> > sensor type and the bottom 8 for an index, if that made dispatching of
> > requests more efficient. Or if some optional hardware was detected as
> > missing, leaving some holes in ID space.
> 
> True. And without a command to convey the list of valid IDs, the
> consumer of the API would have to iterate over the entire 16bit space to
> locate valid IDs.

Or get IDs from device-tree :-) Anyway, I'm not arguing that the IDs
shouldn't be 0..N-1, just that it should explicitly documented in the
SCPI doc, which we're are in agreement on.

-- 
Tixy

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/