linux-kernel - Re: [PATCH] dt-bindings: firmware: arm,scmi: support system power protocol

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Message-ID: <ZeGyES-VOxafuAQx@pluto>
Date: Fri, 1 Mar 2024 10:46:41 +0000
From: Cristian Marussi <cristian.marussi@....com>
To: Peng Fan <peng.fan@....com>
Cc: Sudeep Holla <sudeep.holla@....com>,
	"Peng Fan (OSS)" <peng.fan@....nxp.com>,
	"robh@...nel.org" <robh@...nel.org>,
	"krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>,
	"conor+dt@...nel.org" <conor+dt@...nel.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dt-bindings: firmware: arm,scmi: support system power
 protocol

On Fri, Mar 01, 2024 at 10:37:49AM +0000, Cristian Marussi wrote:
> On Fri, Mar 01, 2024 at 09:22:24AM +0000, Peng Fan wrote:
> > > Subject: Re: [PATCH] dt-bindings: firmware: arm,scmi: support system power
> > > protocol
> > > 
> > > On Fri, Mar 01, 2024 at 12:41:29AM +0000, Peng Fan wrote:
> > > > > Subject: Re: [PATCH] dt-bindings: firmware: arm,scmi: support system
> > > > > power protocol
> > > > >
> > > > > On Tue, Feb 27, 2024 at 01:01:41AM +0000, Peng Fan wrote:
> > > > > > > Subject: Re: [PATCH] dt-bindings: firmware: arm,scmi: support
> > > > > > > system power protocol
> > > > > > >
> > > > > > > On Mon, Feb 26, 2024 at 01:28:31PM +0000, Cristian Marussi wrote:
> > > > > > > > On Mon, Feb 26, 2024 at 09:02:43PM +0800, Peng Fan (OSS) wrote:
> > > > > > > > > From: Peng Fan <peng.fan@....com>
> > > > > > > > >
> > > > > > > > > Add SCMI System Power Protocol bindings, and the protocol id is
> > > 0x12.
> > > > > > > > >
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > yes this is something I spotted in the past it was missing and
> > > > > > > > I posted a similar patch but I was told that a protocol node
> > > > > > > > without any specific additional properties is already being
> > > > > > > > described by the general protocol node described above.
> > > > > >
> > > > > > Without this patch, there is dtbs_check warning.
> > > > > >
> > > > > > scmi: 'protocol@12' does not match any of the regexes: 'pinctrl-[0-9]+'
> > > > > > from schema $id:
> > > > > > https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fd
> > > > > >
> > > evic%2F&data=05%7C02%7Cpeng.fan%40nxp.com%7C3ef5d152a8e5463e9b
> > > 3408
> > > > > >
> > > dc39c47e41%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C63844
> > > 87632
> > > > > >
> > > 86203182%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoi
> > > V2luM
> > > > > >
> > > zIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=kRBV9FPk6
> > > Nrgu
> > > > > > Hs2SHpL74VlNUH6cYO1kAsW74CkaTk%3D&reserved=0
> > > > > >
> > > > >
> > > etree.org%2Fschemas%2Ffirmware%2Farm%2Cscmi.yaml%23&data=05%7C0
> > > > > 2%7Cpen
> > > > > >
> > > > >
> > > g.fan%40nxp.com%7Ccac77deb5f6a4b20460a08dc392ead40%7C686ea1d3b
> > > > > c2b4c6fa
> > > > > >
> > > > >
> > > 92cd99c5c301635%7C0%7C0%7C638448119832543335%7CUnknown%7CT
> > > > > WFpbGZsb3d8e
> > > > > >
> > > > >
> > > yJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D
> > > > > %7C0%
> > > > > >
> > > > >
> > > 7C%7C%7C&sdata=6MldIOUQ4hxn%2BRffwJJJ3jxXXtHCSxLUOa4JMWB0htU%
> > > > > 3D&reserv
> > > > > > ed=0
> > > > > >
> > > > >
> > > > > Why are you adding protocol@12 to the device tree ? Does it have a
> > > > > dedicated channel ? If not, you shouldn't need to add it.
> > > >
> > > > No dedicated channel.
> > > > The idea is we have multile Agent, the M7 agent may ask to shutdown
> > > > Linux Agent. So the linux agent need use protocol@12 to do the action.
> > > >
> > > 
> > > Ok, so indeed you need, AFAICR, the node in the DT even without a dedicated
> > > channel nor anynone referring it: no DT node means no protocol initialization.
> > 
> > Yeah, so this binding update is needed, right?
> > 
> > > 
> > > > For now, we have not finish implementing this in linux side, just add
> > > > the node in dts.
> > > 
> > > On the linux side you should not need to do anything but adding the node
> > > @12, the existent drivers/firmware/arm_scmi/system_power_control.c
> > > driver when loaded will shutdown the system upon receiving the
> > > SytemPower notification....what lacks Linux side in these regards ?
> > 
> > " Ignoring unsupported system_state:" we have new defined
> > number here.
> > 
> 
> So I suppose you are using the Vendor defined system states and writing
> your own driver to handle these instead of system_power_control ?

Or some vendor extensions to the std driver ?
IOW what is the plan...custom vendor states was left out from
system_power_control waiting for a real usecase...that seems to have
shown up eventually :D

Thanks,
Cristian