linux-kernel - Re: [PATCH v1] arm64: dts: ti: k3-am62p: Enable AUDIO

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Message-ID: <20250228124347.GA20656@francesco-nb>
Date: Fri, 28 Feb 2025 13:43:47 +0100
From: Francesco Dolcini <francesco@...cini.it>
To: Nishanth Menon <nm@...com>, Jayesh Choudhary <j-choudhary@...com>,
	Francesco Dolcini <francesco@...cini.it>
Cc: 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>,
	Francesco Dolcini <francesco.dolcini@...adex.com>,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] arm64: dts: ti: k3-am62p: Enable AUDIO_REFCLKx

On Fri, Feb 07, 2025 at 09:33:01AM +0100, Francesco Dolcini wrote:
> On Thu, Feb 06, 2025 at 07:42:39PM -0600, Nishanth Menon wrote:
> > On 16:39-20250206, Francesco Dolcini wrote:
> > > From: Francesco Dolcini <francesco.dolcini@...adex.com>
> > > 
> > > On AM62P-based SoCs the AUDIO_REFCLKx clocks can be used as an input to
> > > external peripherals when configured through CTRL_MMR, so add the
> > > clock nodes.
> > > 
> > > Link: http://downloads.ti.com/tisci/esd/latest/5_soc_doc/am62px/clocks.html
> > > Signed-off-by: Francesco Dolcini <francesco.dolcini@...adex.com>
> > > ---
> > >  arch/arm64/boot/dts/ti/k3-am62p-main.dtsi | 20 ++++++++++++++++++++
> > >  1 file changed, 20 insertions(+)
> > > 
> > > diff --git a/arch/arm64/boot/dts/ti/k3-am62p-main.dtsi b/arch/arm64/boot/dts/ti/k3-am62p-main.dtsi
> > > index 420c77c8e9e5..4b47b0774330 100644
> > > --- a/arch/arm64/boot/dts/ti/k3-am62p-main.dtsi
> > > +++ b/arch/arm64/boot/dts/ti/k3-am62p-main.dtsi
> > > @@ -42,6 +42,26 @@ &inta_main_dmss {
> > >  	ti,interrupt-ranges = <5 69 35>;
> > >  };
> > >  
> > > +&main_conf {
> > 
> > 	Why not add it to main_conf section it self in the file?
> 
> The reason is that main_conf is defined in k3-am62p-j722s-common-main.dtsi,
> that is shared between am62p and j722s.
> 
> On j722s the audio refclk is added in k3-j722s-main.dtsi the same way as I did
> here, so I cannot move this to k3-am62p-j722s-common-main.dtsi without updating
> also k3-j722s-main.dtsi.
> 
> I looked into the differences of j722s and am62p, and from my understanding,
> from the audio refclk point of view, they are identical (same IP, same reg, same
> clocks and same IDs), so this should naturally be moved to
> k3-am62p-j722s-common-main.dtsi as you are suggesting.
> 
> ... however, for some reason I am not aware of, on k3-j722s-main.dtsi a different
> parent clock is used, and I cannot understand the reason. The actual parent clocks
> in this patch are just the same we already have everywhere apart on j722s. I tried
> to look at the history of this and it seems that on the TI downstream kernel branch
> this is defined in the board dts file (!) and this confused me even more.
> 
> So, not wanting to break stuff I was not able to understand I came up with this
> proposal.
> 
> An alternative could be to override the "unexpected" clocks from
> k3-j722s-main.dtsi to the board dts file, and have the "standard" clocks, as
> proposed in this patch and already used on all the other AM62 variants, in
> k3-am62p-j722s-common-main.dtsi.
> 
> +Jayesh that is the author of this specific change in k3-j722s-main.dtsi.

Jayesh, Nishanth, any comment on this?

Should I proceed with this last option ?

   An alternative could be to override the "unexpected" clocks from
   k3-j722s-main.dtsi to the board dts file, and have the "standard" clocks, as
   proposed in this patch and already used on all the other AM62 variants, in
   k3-am62p-j722s-common-main.dtsi.

Francesco