Re: [PATCH 3/3] Documentation: DT bindings: Tegra AHB: note base address change

[Stephen Warren]

I guess pretend like I never made the suggestion.

On 03/19/2015 12:42 PM, Paul Walmsley wrote:
> On Thu, 19 Mar 2015, Stephen Warren wrote:
>
> > On 03/19/2015 10:34 AM, Paul Walmsley wrote:
> > > On Thu, 19 Mar 2015, Stephen Warren wrote:
> > >
> > > > On 03/19/2015 09:33 AM, Paul Walmsley wrote:
> > > > > On Tue, 17 Mar 2015, Stephen Warren wrote:
> > > > >
> > > > > > On 03/17/2015 02:32 AM, Paul Walmsley wrote:
> > > > > > > For Tegra132 and later chips, we can now use the correct hardware
> > > > > > > base
> > > > > > > address for the Tegra AHB IP block in the DT data.  Update the DT
> > > > > > > binding
> > > > > > > documentation to reflect this change.
> > > > > >
> > > > > > > diff --git
> > > > > > > a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-ahb.txt
> > > > > > > b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-ahb.txt
> > > > > > > index 067c979..7692b4c 100644
> > > > > > > ---
> > > > > > > a/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-ahb.txt
> > > > > > > +++
> > > > > > > b/Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-ahb.txt
> > > > > > > @@ -2,10 +2,15 @@ NVIDIA Tegra AHB
> > > > > > >
> > > > > > >      Required properties:
> > > > > > >      - compatible : For Tegra20, must contain "nvidia,tegra20-ahb".
> > > > > > > For
> > > > > > > -  Tegra30, must contain "nvidia,tegra30-ahb".  Otherwise, must
> > > > > > > contain
> > > > > > > -  '"nvidia,<chip>-ahb", "nvidia,tegra30-ahb"' where <chip> is
> > > > > > > tegra124,
> > > > > > > -  tegra132, or tegra210.
> > > > > > > -- reg : Should contain 1 register ranges(address and length)
> > > > > > > +  Tegra30, must contain "nvidia,tegra30-ahb".  For Tegra114 and
> > > > > > > Tegra124,
> > > > > > > must
> > > > > > > +  contain '"nvidia,<chip>-ahb", "nvidia,tegra30-ahb"' where <chip>
> > > > > > > is
> > > > > > > tegra114
> > > > > > > +  or tegra124.  For Tegra132, the compatible string must contain
> > > > > > > +  "nvidia,tegra132-ahb".
> > > > > > > +
> > > > > > > +- reg : Should contain 1 register ranges(address and length).  On
> > > > > > > Tegra20,
> > > > > > > +  Tegra30, Tegra114, and Tegra124 chips, the low byte of the
> > > > > > > physical
> > > > > > > base
> > > > > > > +  address of the IP block must end in 0x04.  On DT files for later
> > > > > > > chips,
> > > > > > > the
> > > > > > > +  actual hardware base address of the IP block should be used.
> > > > > >
> > > > > > A table-based approach rather than prose might make this more legible?
> > > > > >
> > > > > > - compatible: Must contain the following:
> > > > > >      Tegra20:  "nvidia,tegra20-ahb"
> > > > > >      Tegra30:  "nvidia,tegra30-ahb"
> > > > > >      Tegra114: "nvidia,tegra114-ahb", "nvidia,tegra30-ahb"
> > > > > >      Tegra124: "nvidia,tegra124-ahb", "nvidia,tegra30-ahb"
> > > > > >      Tegra132: "nvidia,tegra132-ahb"
> > > > > >      Tegra210: "nvidia,tegra210-ahb", "nvidia,tegra132-ahb"
> > > > > >
> > > > > > With any luck, we can extend that final item for future chips to be:
> > > > > >
> > > > > >      Tegra210, TegraNNN:
> > > > > >                "nvidia,tegra<chip>-ahb", "nvidia,tegra132-ahb"
> > > > > >
> > > > > > Perhaps we format the 114/124 entry that way too.
> > > > >
> > > > > I think I'm just going to drop this patch, since Russell prefers that
> > > > > the
> > > > > workaround is applied in the driver.
> > > > >
> > > > > With regards to using tables rather than narrative descriptions: perhaps
> > > > > consider a patch to
> > > > > Documentation/devicetree/bindings/submitting-patches.txt ?  I don't know
> > > > > what the DT binding documentation maintainers' future plans are with
> > > > > regards to automated documentation reflow, etc., but submitting a patch
> > > > > there would stimulate at least some coordination on the issue.
> > > >
> > > > I don't think it's appropriate for that file to dictate that, in the same
> > > > way
> > > > that coding style documentation generally doesn't address that kind of
> > > > detail
> > > > regarding code structure.
> > >
> > > We do indeed specify details like this in our documentation guidelines.
> > > Here are two examples:
> > >
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/kernel-doc-nano-HOWTO.txt#n103
> > >
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/CodingStyle#n464
> >
> > Perhaps I phrased my point slightly differently form the core of what I meant.
> >
> > I'm not aware that review feedback can't address topics that are not already
> > addressed by the documentation. Is there such a rule?
>
> Not that I'm aware of, but I'm not sure that I understand the point you're
> making.  Care to rephrase to make it more explicit?
>
> > Equally, I think if you want the documentation to address a particular point,
> > it's appropriate for you to submit a patch to the documentation to update it,
> > rather than ask the reviewer to do so before accepting the review feedback.
>
> I guess my question is this: do you intend that the table-based
> documentation approach you describe should apply generally to other DT
> binding documents with similar per-chip support lists?  Or is there
> something about the Tegra AHB specifically that merits this format?
>
> If the former was intended -- in other words, you are proposing a policy
> that should be followed in the general case -- then I would suggest that
> the documentation policy should be described in a shared DT binding
> CodingStyle or submitting-patches document, as we do elsewhere in the
> kernel.
>
> For example, the guidance could read[*], using your earlier example:
>
> ---
> If different values of a DT property are required for different chips
> or different situations, these should be listed in the binding
> documentation in the following format:
>
> - compatible: Must contain the following:
>      Tegra20:  "nvidia,tegra20-ahb"
>      Tegra30:  "nvidia,tegra30-ahb"
>      Tegra114: "nvidia,tegra114-ahb", "nvidia,tegra30-ahb"
> (etc.)
>
> Each line in the list should be indented from the start of the section
> describing the DT property by four spaces.  There should be no blank
> lines between each list row.
> ---
>
> That way, the community can align on a common format for this table-based
> format.  Any automated parsing tools that read the DT documentation can
> know what to expect; anyone who disagrees can speak up as the patch is
> being considered; and the issue no longer needs to be a matter of taste:
> it can be transformed into a matter of fact.
>
> Once the documentation format becomes a matter of fact, then patch
> submitters have clear guidance to follow.  Submitters can get the patches
> right the first time and avoid wasting their time and reviewers' time.
> Otherwise, there is the (quite present) risk that 'n' different reviewers
> of the DT binding documentation could have 'n' different opinions about
> how the data should be formatted, with each opinion conveying
> minimal-to-no technical advantage over another.  This just results in a
> waste of time for everyone, time that is better spent on code.  In my
> view, every moment I spend reformatting documentation to standards that
> aren't shared is not only wasted, it's time that's subtracted from my
> ability to improve our actual upstream code and work on something that's
> actually useful.
>
>
> - Paul
>
> [*] I am neutral about the format or whether a narrative vs. a table
> approach is best.  Whatever it should be, it should just be common
> guidance.

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