Re: [PATCH 08/22] dt-bindings: display: rockchip: dw-hdmi: use "ref" as clock name

Rob Herring
2021-12-22T13:54:44Z

On Wed, Dec 22, 2021 at 6:47 AM Sascha Hauer <s.hauer@pengutronix.de> wrote:
>
> On Tue, Dec 21, 2021 at 10:31:23AM -0400, Rob Herring wrote:
> > On Mon, Dec 20, 2021 at 12:06:16PM +0100, Sascha Hauer wrote:
> > > "vpll" is a misnomer. A clock input to a device should be named after
> > > the usage in the device, not after the clock that drives it. On the
> > > rk3568 the same clock is driven by the HPLL.
> > > To fix that, this patch renames the vpll clock to ref clock.
> >
> > The problem with this series is it breaks an old kernel with new dt. You
> > can partially mitigate that with stable kernel backport, but IMO keeping
> > the old name is not a burden to maintain.
>
> As suggested I only removed vpll from the binding document, but not from
> the code. The code still handles the old binding as well.

The problem is updating rk3399.dtsi. That change won't work with old
kernels because they won't look for 'ref'. Since you shouldn't change
it, the binding needs to cover both the old and new cases.

Rob