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

[Jon Medhurst (Tixy)]

On Tue, 2015-09-15 at 17:04 +0100, Punit Agrawal wrote:
> "Jon Medhurst (Tixy)" <tixy@xxxxxxxxxx> writes:
> 
> > On Tue, 2015-09-15 at 10:37 +0100, Punit Agrawal wrote:
> >> "Jon Medhurst (Tixy)" <tixy@xxxxxxxxxx> writes:
> >> 
> >> > On Mon, 2015-09-14 at 15:38 +0100, Punit Agrawal wrote:
> >> >> Mark Rutland <mark.rutland@xxxxxxx> 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

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