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

[AngeloGioacchino Del Regno]

Il 27/10/22 11:40, Konrad Dybcio ha scritto:
> On 27/10/2022 11:28, AngeloGioacchino Del Regno wrote:
> > 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-$(CONFIG_ARCH_MEDIATEK) += mt6795-sony-xperia-m5.dtb
> > > -holly.dtb?
> >
> > I prefer using the commercial name to identify the device.
> > "Holly" is the smartphone project codename and that is mentioned almost nowhere:
> > the aim here is to enhance readability as to make it immediately understandable
> > that this devicetree is for the Xperia M5 device.
>
> Ok, sounds good.
>
>
> > > >   dtb-$(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".
>
> I was suggesting replacing xperia-m5 with holly, but since we agreed on keeping
>
> m5 in the dtb name, I suppose it's fine for this one to stay too.
>
>
> > 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).
>
> Ugh. If only vendors tested their software before shipping it to users..
>
> I think it's worth to adding a comment mentioning that, though.
>
>
> > > > +    };
> > > > +
> > > > +    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.

Sorry again, I forgot to reply to this question, so addressing that now:
no, that's not true for all devices with this SoC.

I'm practically sure that all commercial devices that were shipped at that time
require the same, but here upstream we also have a MT6795 dev board devicetree,
which uses a much newer bootloader and possibly needs a different secmon carveout,
if any at all.

Hence, this one cannot be transferred to mt6795.dtsi.