linux-kernel - Re: [PATCH 1/2] arm64: dts: ti: k3-am65: add boot phase tags

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Message-ID: <20250710123337.ltnfhtpxaisi2yu3@bryanbrattlof.com>
Date: Thu, 10 Jul 2025 07:33:37 -0500
From: Bryan Brattlof <bb@...com>
To: Vignesh Raghavendra <vigneshr@...com>
CC: Nishanth Menon <nm@...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>
Subject: Re: [PATCH 1/2] arm64: dts: ti: k3-am65: add boot phase tags

On July 10, 2025 thus sayeth Vignesh Raghavendra:
> 
> 
> On 10/07/25 04:05, Bryan Brattlof wrote:
> 
> [...]
> 
> > diff --git a/arch/arm64/boot/dts/ti/k3-am65-mcu.dtsi b/arch/arm64/boot/dts/ti/k3-am65-mcu.dtsi
> > index 7cf1f646500a16c1d1bac6dfb37fb285218063b3..5bbd817bc51464f6605c5b2dc9cb544a109a695d 100644
> > --- a/arch/arm64/boot/dts/ti/k3-am65-mcu.dtsi
> > +++ b/arch/arm64/boot/dts/ti/k3-am65-mcu.dtsi
> > @@ -211,6 +211,7 @@ mcu_ringacc: ringacc@...00000 {
> >  			ti,sci = <&dmsc>;
> >  			ti,sci-dev-id = <195>;
> >  			msi-parent = <&inta_main_udmass>;
> > +			bootph-all;
> >  		};
> >  
> >  		mcu_udmap: dma-controller@...c0000 {
> > @@ -235,6 +236,7 @@ mcu_udmap: dma-controller@...c0000 {
> >  			ti,sci-rm-range-rchan = <0xb>, /* RX_HCHAN */
> >  						<0xa>; /* RX_CHAN */
> >  			ti,sci-rm-range-rflow = <0x0>; /* GP RFLOW */
> > +			bootph-all;
> >  		};
> >  	};
> 
> Should this be board specific property? Does every user of AM65x need
> DMA at boot stage?
> 

Yeah. I'm not too sure how we want to handle this. Some boot modes will 
require DMA up and running, but if a board only uses eMMC then we won't 
need DMA during the early phases of boot.

I saw we already do this for the AM62P so I decided to keep moving in 
that direction even though it's not a perfect and it seemed like a 
better solution than dragging the DMA node up to the board level.

I'll drop it for now until I can think of a better idea.

> [...]
> 
> > @@ -107,5 +111,6 @@ wkup_vtm0: temperature-sensor@...50000 {
> >  		reg = <0x42050000 0x25c>;
> >  		power-domains = <&k3_pds 80 TI_SCI_PD_EXCLUSIVE>;
> >  		#thermal-sensor-cells = <1>;
> > +		bootph-all;
> 
> Same here..
> 

Yeah I'm assuming this is one of those weird things being in the middle 
of the Jacinto and Sitara class causes. It's used, much like the rest of 
the Jacinto parts, by the bootloaders to get at the voltage domain info 
to configure the OPP data before the bootloader starts the A53s.

All AM65x boards will need this node to prevent an overclocking situation 
if the voltage isn't high enough.

~Bryan