linux-kernel - Re: [PATCH 10/15] arm64: dts: qcom: Add MSM8953 device tree

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Message-ID: <4689218.GXAFRqVoOG@g550jk>
Date:   Sat, 19 Feb 2022 12:50:52 +0100
From:   Luca Weiss <luca@...tu.xyz>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     linux-arm-msm@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        Vladimir Lypak <vladimir.lypak@...il.com>,
        Andy Gross <agross@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/15] arm64: dts: qcom: Add MSM8953 device tree

Hi Bjorn,

On Dienstag, 15. Februar 2022 17:40:20 CET Bjorn Andersson wrote:
> On Wed 12 Jan 13:40 CST 2022, Luca Weiss wrote:
> > From: Vladimir Lypak <vladimir.lypak@...il.com>
> > 
> > Add a base DT for MSM8953 SoC.
> > 
> > Co-developed-by: Luca Weiss <luca@...tu.xyz>
> > Signed-off-by: Vladimir Lypak <vladimir.lypak@...il.com>
> > Signed-off-by: Luca Weiss <luca@...tu.xyz>
> > ---
> > 
> >  arch/arm64/boot/dts/qcom/msm8953.dtsi | 1337 +++++++++++++++++++++++++
> >  1 file changed, 1337 insertions(+)
> >  create mode 100644 arch/arm64/boot/dts/qcom/msm8953.dtsi
> > 
> > diff --git a/arch/arm64/boot/dts/qcom/msm8953.dtsi
> > b/arch/arm64/boot/dts/qcom/msm8953.dtsi new file mode 100644
> > index 000000000000..59918b527750
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/qcom/msm8953.dtsi
> > @@ -0,0 +1,1337 @@
> > +// SPDX-License-Identifier: BSD-3-Clause
> > +/* Copyright (c) 2022, The Linux Foundation. All rights reserved. */
> > +
> > +#include <dt-bindings/clock/qcom,gcc-msm8953.h>
> > +#include <dt-bindings/gpio/gpio.h>
> > +#include <dt-bindings/interrupt-controller/arm-gic.h>
> > +#include <dt-bindings/power/qcom-rpmpd.h>
> > +#include <dt-bindings/thermal/thermal.h>
> > +
> > +/ {
> > +	interrupt-parent = <&intc>;
> > +
> > +	#address-cells = <2>;
> > +	#size-cells = <2>;
> 
> Why do you have address/size-cells of 2, and then limit them to 1 in
> /soc?

Quite a few arm64 qcom dtsi files use #address-cells & #size-cells = <1> which 
also makes reg properties quite more readable - and we don't need the 64 bits 
on 8953.

> 
> > +
> > +	aliases {
> > +		i2c1 = &i2c_1;
> > +		i2c2 = &i2c_2;
> > +		i2c3 = &i2c_3;
> > +		i2c4 = &i2c_4;
> > +		i2c5 = &i2c_5;
> > +		i2c6 = &i2c_6;
> > +		i2c7 = &i2c_7;
> > +		i2c8 = &i2c_8;
> 
> It was expressed a while back that you should specify alias only for the
> things that you have enabled in your .dts.

Sure, I'll remove it.

> 
> > +	};
> 
> [..]
> 
> > +		tcsr_mutex: hwlock@...5000 {
> > +			compatible = "qcom,tcsr-mutex";
> > +			reg = <0x1905000 0x20000>;
> > +			#hwlock-cells = <1>;
> > +		};
> > +
> > +		tcsr: syscon@...7000 {
> > +			compatible = "qcom,tcsr-msm8953", "syscon";
> > +			reg = <0x1937000 0x30000>;
> > +		};
> > +
> > +		tcsr_phy_clk_scheme_sel: syscon@...f044 {
> 
> I don't fancy exposing a single word from the middle of &tcsr using a
> syscon. The tcsr node should express the TCSR region and if we need to
> reference bits of information within that we should do that in some
> structured way.
> 
> Wouldn't nvmem be a good candidate for this?

The qusb2 bindings expect the reference like this as far as I can tell, 

qphy->tcsr = syscon_regmap_lookup_by_phandle(dev->of_node,
                                           "qcom,tcsr-syscon");

So I don't think we can change this without changing the driver as well?

Regards
Luca

> 
> > +			compatible = "syscon";
> > +			reg = <0x193f044 0x4>;
> > +		};
> > +
> 
> Regards,
> Bjorn