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From: Jerome Brunet <>
To: Rob Herring <>,
	Kevin Hilman <>,
	Neil Armstrong <>
Cc: Carlo Caione <>,,,,,
Subject: Re: [PATCH 1/4] dt-bindings: clock: meson: update documentation with hhi syscon
Date: Sun, 18 Mar 2018 16:09:57 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20180318125222.kqtybu4hiwvsx3om@rob-hp-laptop>

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

  reply	other threads:[~2018-03-18 15:10 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-15 11:55 [PATCH 0/4] ARM64: dts: meson: hhi syscon and clock controllers Jerome Brunet
2018-03-15 11:55 ` [PATCH 1/4] dt-bindings: clock: meson: update documentation with hhi syscon Jerome Brunet
2018-03-18 12:52   ` Rob Herring
2018-03-18 15:09     ` Jerome Brunet [this message]
2018-03-23  3:04       ` Rob Herring
2018-03-26  7:49         ` Neil Armstrong
2018-03-15 11:55 ` [PATCH 2/4] ARM64: dts: meson-gx: sysctrl is the parent of the clock controller Jerome Brunet
2018-03-15 11:55 ` [PATCH 3/4] ARM64: dts: meson-axg: use hhi syscon for " Jerome Brunet
2018-03-15 11:55 ` [PATCH 4/4] ARM64: dts: meson-gx: fix gxl clock controller compatible Jerome Brunet
2018-04-19 17:41 ` [PATCH 0/4] ARM64: dts: meson: hhi syscon and clock controllers Kevin Hilman

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