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Re: [Qemu-devel] [RFC PATCH 0/6] Clock and power gating support

From: Mark Burton
Subject: Re: [Qemu-devel] [RFC PATCH 0/6] Clock and power gating support
Date: Mon, 30 Jul 2018 15:17:16 +0200
User-agent: AquaMail/1.16.0-1193 (build: 101600006)

Hi Pete, sorry for the tardy reply, Im not in the office.

Your right  we shoujd have co-ordinated better the 2 patches, sorry for that.

Regarding this new patchset, we think there is a degree of complementary to the
clocktree one.
Here we simply add a couple of generic power states to a device. We
an interface to control power and clock gating on any devices, with sensible
generic behaviour (reset on power on, disabling memory regions when
asleep or
off). The device can specialize this to adopt specific behaviours.

It allows easy implementation of commonly found "system controller", "pin
controllers", "power management unit", or similar blocks in SoCs.
Specialization of devices can be implemented as-needed when a machine


On 27 July 2018 17:22:30 KONRAD Frederic <address@hidden> wrote:

Le 07/27/2018 à 04:59 PM, Peter Maydell a écrit :
On 27 July 2018 at 15:37, Damien Hedde <address@hidden> wrote:
This set of patches add support for power and clock gating in device objects.
It adds two booleans to the state, one for power state and one of clock state.

The state is controlled trough 2 functions, one for power and one for clock.
Two new methods *power_update* and *clock_update* is added to the device class
which are called on state change and can be overriden.

So, you folks at Greensocs had a series a couple of years ago to try
to add clocktree support (which included handling things like guests
configuring clock rates, some clocks being "downstream" of others, and
so on). It didn't make it into mainline, though it did get a fair amount
of design/code review. How does this approach fit into / compare with
that ?

-- PMM

Hi all,

I didn't have time to push a new version of the clock series and
I lost the track a little bit (was 13 months ago). Sorry for
that :(.. Would be still nice to have I think.


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