Re: [PATCH 7/7] arm64: dts: mediatek: Add support for MT6795 Sony Xperia M5 smartphone

[AngeloGioacchino Del Regno]

Il 29/07/22 14:00, Konrad Dybcio ha scritto:
> On 29.07.2022 12:44, AngeloGioacchino Del Regno wrote:
> > Add a basic support for the Sony Xperia M5 (codename "Holly")
> > smartphone, powered by a MediaTek Helio X10 SoC.
> >
> > This achieves a console boot.
> >
> > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>

Hello Konrad,
First of all, I'm sorry for the very late reply.

> > ---
> >   arch/arm64/boot/dts/mediatek/Makefile         |  1 +
> >   .../dts/mediatek/mt6795-sony-xperia-m5.dts    | 90 +++++++++++++++++++
> >   2 files changed, 91 insertions(+)
> >   create mode 100644 arch/arm64/boot/dts/mediatek/mt6795-sony-xperia-m5.dts
> >
> > diff --git a/arch/arm64/boot/dts/mediatek/Makefile b/arch/arm64/boot/dts/mediatek/Makefile
> > index af362a085a02..72fd683c9264 100644
> > --- a/arch/arm64/boot/dts/mediatek/Makefile
> > +++ b/arch/arm64/boot/dts/mediatek/Makefile
> > @@ -3,6 +3,7 @@ dtb-$(CONFIG_ARCH_MEDIATEK) += mt2712-evb.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt6755-evb.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt6779-evb.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt6795-evb.dtb
> > +dtb-$(CONFIG_ARCH_MEDIATEK) += mt6795-sony-xperia-m5.dtb
> -holly.dtb?

I prefer using the commercial name to identify the device.
"Holly" is the smartphone project codename and that is mentioned almost nowhere:
the aim here is to enhance readability as to make it immediately understandable
that this devicetree is for the Xperia M5 device.

> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt6797-evb.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt6797-x20-dev.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt7622-rfb1.dtb
> > diff --git a/arch/arm64/boot/dts/mediatek/mt6795-sony-xperia-m5.dts b/arch/arm64/boot/dts/mediatek/mt6795-sony-xperia-m5.dts
> > new file mode 100644
> > index 000000000000..94d011c4126c
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/mediatek/mt6795-sony-xperia-m5.dts
> > @@ -0,0 +1,90 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (c) 2022, Collabora Ltd
> > + * Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > + */
> > +
> > +/dts-v1/;
> > +#include "mt6795.dtsi"
> > +
> > +#include <dt-bindings/gpio/gpio.h>
> Looks unused.

Right, I'll remove that in v2.

> > +
> > +/ {
> > +	model = "Sony Xperia M5";
> > +	compatible = "sony,xperia-m5", "mediatek,mt6795";
> sony,holly?

I'm sorry, but I can't understand the sense of adding that compatible string to
the mix. To the kernel, it doesn't mean anything - and we already have another
string advertising the specific machine, which is "sony,xperia-m5".

Of course, there is no Xperia M5 with a different SoC and, even if there was a
xperia-m5 with a different SoC, we anyway have both a machine compatible and a
SoC compatible in here, so that would still not pose any issue.

> > +	chassis-type = "handset";
> > +
> > +	aliases {
> > +		mmc0 = &mmc0;
> > +		mmc1 = &mmc1;
> > +		serial0 = &uart0;
> > +		serial1 = &uart1;
> > +	};
> > +
> > +	memory@40000000 {
> > +		device_type = "memory";
> > +		reg = <0 0x40000000 0 0x1E800000>;
> Lowercase hex in size. Also, doesn't the bootloader fill it in?

Updating the device to the latest software version will give you a bootloader
that fills that in, but the first-ever software release contains one that will
not do that in particular conditions (fastboot boot).

> > +	};
> > +
> > +	reserved_memory: reserved-memory {
> > +		#address-cells = <2>;
> > +		#size-cells = <2>;
> > +		ranges;
> > +
> > +		/* 128 KiB reserved for ARM Trusted Firmware (BL31) */
> Is that true for all devices with this SoC, or..? If so, it may be worth
> moving this into mt6795.dtsi.
>
> > +		bl31_secmon_reserved: secmon@43000000 {
> memory@, everywhere. Use labels to name the nodes.

I'm afraid that's not possible, as the bootloader is reading the devicetree
and requires these nodes to follow this naming.

> > +			no-map;
> reg goes first.

Will fix in v2.

Best regards,
Angelo