Re: [PATCH v7 4/5] ARM: tegra: Add efuse and apbmisc bindings

Peter De Schrijver
2014-06-06T07:35:48Z

On Fri, Jun 06, 2014 at 12:55:22AM +0200, Stephen Warren wrote:
> On 06/05/2014 04:13 PM, Peter De Schrijver wrote:
> > On Thu, Jun 05, 2014 at 08:41:55PM +0200, Stephen Warren wrote:
> >> On 06/05/2014 07:09 AM, Peter De Schrijver wrote:
> >>> Add efuse and apbmisc bindings for Tegra20, Tegra30, Tegra114 and Tegra124.
> >>
> >>> diff --git a/arch/arm/boot/dts/tegra114.dtsi b/arch/arm/boot/dts/tegra114.dtsi
> >>
> >>> + apbmisc@70000800 {
> >>> + compatible = "nvidia,tegra114-apbmisc", "nvidia,tegra20-apbmisc";
> >>
> >> Is the Tegra114 APBMISC register layout 100% a backwards-compatible
> >> superset of that in Tegra20? For both registers the code currently uses
> >> *and* all possible registers the code could ever use? Since the APB MISC
> >> is a bit of a dumping ground for random registers, that feels unlikely,
> >> but perhaps it's possible.
> >
> > For all I can see it is. At least for the registers the kernel is likely to
> > use.
>
> But that's ("At least for the registers the kernel is likely to use")
> not how compatible values are defined. We need to explicitly look at all
> the registers and actively decide that it really is compatible in order
> to mark it so. If we don't want to do that, it's best just to use a
> separate compatible value for each SoC, and add a couple more entries
> into the match table.

All the other registers are for all I can see only useful in emulation
environments.

Cheers,

Peter.