On Mittwoch, 22. Dezember 2021 20:39:58 CET Heiko Stübner wrote:
Am Mittwoch, 22. Dezember 2021, 14:52:51 CET schrieb Rob Herring:
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.
is "newer dt with old kernel" really a case these days?
I do understand the new kernel old dt case - for example with the dtb being provided by firmware.
But which user would get the idea of updating only the devicetree while staying with an older kernel?
Side-by-side installations of LTS kernels with new kernels. LTS kernel uses same DT as new kernel because distribution set it up this way.
Other scenario: user wants to modify their device tree. They download the latest kernel sources from kernel.org because they can't use over- lays and they don't want to fiddle with decompiled device trees.