Re: [PATCH v4 1/3] media: dt-bindings: rockchip,vdec: Add alternative reg-names order for RK35{76,88}

[Krzysztof Kozlowski <krzk@kernel.org>]

On Thu, Feb 26, 2026 at 06:43:31PM +0000, Conor Dooley wrote:
> On Thu, Feb 26, 2026 at 12:46:53PM +0200, Cristian Ciocaltea wrote:
> > With the introduction of the RK3588 SoC, and RK3576 afterwards, two more
> > register blocks have been provided for the video decoder unit.
> > 
> > However, the binding does not properly describe the new hardware layout,
> > as it breaks the convention expecting the unit address to indicate the
> > start of the first register range, i.e. 'function' block is listed
> > before 'link' instead of the opposite.
> 
> I don't understand this commit message or rationale for an ABI break.


The description is indeed wrong. The binding properly describes new
hardware layout. They just don't like it.

Hardware has three separate address spaces and EXACT three correct
separate address spaces are described the binding.

> Changing the unit address seems like a "free" fix to your problem,
> especially when reg-names is not a required property that you can rely
> on. Actually, there may be a bug in the driver - it expects reg-names
> for rk3576-vdec and rk3588-vdec but the binding doesn't mandate their
> presence for those devices.
> 
> Deprecating the order also makes little sense to me, given that some of
> these devices only have one reg entry, which as far as I can tell from
> looking at the driver *is* the "function" region, so it can never be
> entirely deprecated.

There is "if" at the bottom of the binding, so the one entry does not
use reg-names.

Best regards,
Krzysztof