[PATCH 1/4] dt-bindings: clock: meson: update documentation with hhi syscon
Jerome Brunet
jbrunet at baylibre.com
Sun Mar 18 08:09:57 PDT 2018
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 at 0
which is used by the display device.
and in arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi (same for gxl)
> clock-controller at 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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