From: Lars Povlsen <lars.povlsen@microchip.com>
To: Sebastian Reichel <sre@kernel.org>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>,
"Microchip Linux Driver Support" <UNGLinuxDriver@microchip.com>,
<linux-pm@vger.kernel.org>,
"Lars Povlsen" <lars.povlsen@microchip.com>
Subject: Re: [PATCH 3/5] dt-bindings: reset: ocelot: Add documentation for 'microchip,reset-switch-core' property
Date: Wed, 16 Sep 2020 10:00:51 +0200 [thread overview]
Message-ID: <875z8ei218.fsf@soft-dev15.microsemi.net> (raw)
In-Reply-To: <871rjnxm5h.fsf@soft-dev15.microsemi.net>
Lars Povlsen writes:
> Sebastian Reichel writes:
>
>> Hi,
>>
>> On Tue, Jun 02, 2020 at 11:49:08AM +0200, Lars Povlsen wrote:
>> > Rob Herring writes:
>> > > On Wed, May 13, 2020 at 03:08:40PM +0200, Lars Povlsen wrote:
>> > >> This documents the 'microchip,reset-switch-core' property in the
>> > >> ocelot-reset driver.
>> > >>
>> > >> Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
>> > >> ---
>> > >> .../devicetree/bindings/power/reset/ocelot-reset.txt | 6 ++++++
>> > >> 1 file changed, 6 insertions(+)
>> > >>
>> > >> diff --git a/Documentation/devicetree/bindings/power/reset/ocelot-rese=
>> t.txt b/Documentation/devicetree/bindings/power/reset/ocelot-reset.txt
>> > >> index 4d530d8154848..20fff03753ad2 100644
>> > >> --- a/Documentation/devicetree/bindings/power/reset/ocelot-reset.txt
>> > >> +++ b/Documentation/devicetree/bindings/power/reset/ocelot-reset.txt
>> > >> @@ -9,9 +9,15 @@ microchip Sparx5 armv8 SoC's.
>> > >> Required Properties:
>> > >> - compatible: "mscc,ocelot-chip-reset" or "microchip,sparx5-chip-res=
>> et"
>> > >>
>> > >> +Optional properties:
>> > >> +- microchip,reset-switch-core : Perform a switch core reset at the
>> > >> + time of driver load. This is may be used to initialize the switch
>> > >> + core to a known state (before other drivers are loaded).
>> > >
>> > > How do you know when other drivers are loaded? This could be a module
>> > > perhaps. Doesn't seem like something that belongs in DT.
>> > >
>> >
>> > The reset driver is loaded at postcore_initcall() time, which ensures it
>> > is loaded before other drivers using the switch core. I noticed other
>> > drivers do the same to do low-level system reset and initialization at
>> > early boot time.
>> >
>> > > Can this behavior be implied with "microchip,sparx5-chip-reset"?
>> >
>> > Since we need to cater for both modus operandi, I would need two driver
>> > compatible strings per platform, which scales worse than a single
>> > property.
>> >
>> > The "microchip,reset-switch-core" is a device configuration property
>> > which tells the system (driver) how the hw should be handled. Since you
>> > do not *always* want to reset the switch core (f.ex. when implementing
>> > systems with warm reboot), I think it makes perfect sense - but I may be
>> > biased off course :-)
>> >
>> > Thank you for (all) of your comments, by the way!
>> >
>> > ---Lars
>> > > Rob
>>
>> Is this series still needed? Did I miss a follow-up?
>
> Hi Sebastian!
>
> Yes, the series is still needed, but the conversation died after my
> last message.
>
> If the DT-controlled reset property is too controversial, I am willing
> to drop that part. (Rob just reviewed the bindings).
>
> MCHP reference designs have GPIO resets, so we *could* get by without,
> but new designs may this feature.
>
>> -- Sebastian
>
Sebastian,
Any update on the patches? They're the last part of the original Sparx5
series, so I would love to get them done.
As previously stated, I could remove the "microchip,reset-switch-core"
parts if that's whats what holding it stuck.
---Lars
--
Lars Povlsen,
Microchip
next prev parent reply other threads:[~2020-09-16 8:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 13:08 [PATCH 0/5] power: Adding support for Microchip Sparx5 SoC Lars Povlsen
2020-05-13 13:08 ` [PATCH 1/5] dt-bindings: reset: ocelot: Add Sparx5 support Lars Povlsen
2020-05-13 13:08 ` [PATCH 2/5] power: reset: ocelot: Add support for Sparx5 Lars Povlsen
2020-05-13 13:08 ` [PATCH 3/5] dt-bindings: reset: ocelot: Add documentation for 'microchip,reset-switch-core' property Lars Povlsen
2020-05-28 2:25 ` Rob Herring
2020-06-02 9:49 ` Lars Povlsen
[not found] ` <20200828163916.g6vbk3anfyijl7sx@earth.universe>
2020-08-31 8:19 ` Lars Povlsen
2020-09-16 8:00 ` Lars Povlsen [this message]
2020-09-29 22:04 ` Sebastian Reichel
2020-05-13 13:08 ` [PATCH 4/5] power: reset: ocelot: Add support for reset switch on load time Lars Povlsen
2020-05-13 13:08 ` [PATCH 5/5] arm64: dts: sparx5: Add reset support Lars Povlsen
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