linux-kernel - Re: [PATCH v7 06/11] arm64: dts: ti: k3-am62a7-sk: Enable IPC with remote processors

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Message-ID: <20250421114042.riw2kw472murjzcc@surfer>
Date: Mon, 21 Apr 2025 06:40:42 -0500
From: Nishanth Menon <nm@...com>
To: Bryan Brattlof <bb@...com>
CC: Judith Mendez <jm@...com>, Vignesh Raghavendra <vigneshr@...com>,
        Tero
 Kristo <kristo@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof
 Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Hari Nagalla <hnagalla@...com>,
        Beleswar
 Prasad <b-padhi@...com>, Andrew Davis <afd@...com>,
        Markus Schneider-Pargmann
	<msp@...libre.com>,
        Devarsh Thakkar <devarsht@...v0571a.ent.ti.com>
Subject: Re: [PATCH v7 06/11] arm64: dts: ti: k3-am62a7-sk: Enable IPC with
 remote processors

On 10:04-20250419, Bryan Brattlof wrote:
> On April 15, 2025 thus sayeth Judith Mendez:
> > From: Devarsh Thakkar <devarsht@...com>
> > 
> > For each remote proc, reserve memory for IPC and bind the mailbox
> > assignments. Two memory regions are reserved for each remote processor.
> > The first region of 1MB of memory is used for Vring shared buffers
> > and the second region is used as external memory to the remote processor
> > for the resource table and for tracebuffer allocations.
> > 
> > Signed-off-by: Devarsh Thakkar <devarsht@...com>
> > Signed-off-by: Hari Nagalla <hnagalla@...com>
> > Signed-off-by: Judith Mendez <jm@...com>
> > Acked-by: Andrew Davis <afd@...com>
> > Reviewed-by: Beleswar Padhi <b-padhi@...com>
> > Reviewed-by: Jai Luthra <jai.luthra@...asonboard.com>
> > ---
> >  arch/arm64/boot/dts/ti/k3-am62a7-sk.dts | 96 +++++++++++++++++++++++--
> >  1 file changed, 90 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts b/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
> > index 1c9d95696c839..7d817b447c1d0 100644
> > --- a/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
> > +++ b/arch/arm64/boot/dts/ti/k3-am62a7-sk.dts
> > @@ -52,6 +52,42 @@ linux,cma {
> >  			linux,cma-default;
> >  		};
> >  
> > +		c7x_0_dma_memory_region: c7x-dma-memory@...00000 {
> > +			compatible = "shared-dma-pool";
> > +			reg = <0x00 0x99800000 0x00 0x100000>;
> > +			no-map;
> > +		};
> > +
> > +		c7x_0_memory_region: c7x-memory@...00000 {
> > +			compatible = "shared-dma-pool";
> > +			reg = <0x00 0x99900000 0x00 0xf00000>;
> > +			no-map;
> > +		};
> > +
> 
> I know this has been a push for our IPC and MCU+ teams for a couple 
> windows now, though I do want to point out that some AM62A devices 
> (AM62A12AQMSIAMBRQ1) will not even have a C7x. 
> 
> It's relatively easy to cut nodes out that describe the hardware in the 
> bootloaders, but once we start configuring them to demo something it 
> becomes impossible to unwind that during boot.
> 
> We can clam we only support the superset devices but I just wanted to 
> make this email so I could point people to it when they inevitably ask 
> why their parts do not work out of the box with Linux.
> 
> Naked-by: Bryan Brattlof <bb@...com>


I am confused. I do not see support for AM62A1 in upstream. We have
AM62A7-SK in upstream. I am not sure what direction you are suggesting
here.

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D