Messages in this thread | | | Subject | Re: [PATCH 1/4] dt-bindings: clock: meson: update documentation with hhi syscon | From | Jerome Brunet <> | Date | Sun, 18 Mar 2018 16:09:57 +0100 |
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On Sun, 2018-03-18 at 07:52 -0500, Rob Herring wrote: > On Thu, Mar 15, 2018 at 12:55:42PM +0100, Jerome Brunet wrote: > > The HHI register region hosts more than just clocks and needs to > > accessed drivers other than the clock controller, such as the display > > driver. > > > > This register region should be managed by syscon. It is already the case > > on gxbb/gxl and it soon will be on axg. The clock controllers must use > > this system controller instead of directly mapping the registers. > > Sounds like a kernel problem, not a DT one.
It's a platform problem, so it has much a kernel problem (solution already merged) as a DT problem
DT wise, we've got two devices mapping the same region
in arch/arm64/boot/dts/amlogic/meson-gx.dtsi: > system-controller@0
which is used by the display device.
and in arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi (same for gxl) > clock-controller@0
It has worked so far because the clock controller claims the region w/o reserving it but it remains unsafe since both device may access the same region. The fix is to have the clock controller go through the existing syscon.
> > > > > With a single child, there is really no point to this change. A single > node can provide multiple functions. Look at nodes that are both reset > and clock providers.
There is more than a single user, as explained above and in the cover letter of this series.
> > What other functions are there? > > Rob
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