Re: [PATCH 1/1] arm: dts: Enable device-tree overlay support for sun8i-h3 pi devices

["Jernej Škrabec" <jernej.skrabec@gmail.com>]

Dne torek, 27. junij 2023 ob 15:37:03 CEST je Felix Moessbauer napisal(a):
> Add the '-@' DTC option for the sun8i-h3 pi-class devices. This option
> populates the '__symbols__' node that contains all the necessary symbols
> for supporting device-tree overlays (for instance from the firmware or
> the bootloader) on these devices.
> 
> These devices allow various modules to be connected and this enables
> users to create out-of-tree device-tree overlays for these modules.
> 
> Please note that this change does increase the size of the resulting DTB
> by ~30%. For example, with v6.4 increase in size is as follows:
> 
> 22909 -> 29564 sun8i-h3-orangepi-lite.dtb
> 24214 -> 30935 sun8i-h3-bananapi-m2-plus.dtb
> 23915 -> 30664 sun8i-h3-nanopi-m1-plus.dtb
> 22969 -> 29537 sun8i-h3-nanopi-m1.dtb
> 24157 -> 30836 sun8i-h3-nanopi-duo2.dtb
> 24110 -> 30845 sun8i-h3-orangepi-plus2e.dtb
> 23472 -> 30037 sun8i-h3-orangepi-one.dtb
> 24600 -> 31410 sun8i-h3-orangepi-plus.dtb
> 23618 -> 30230 sun8i-h3-orangepi-2.dtb
> 22170 -> 28548 sun8i-h3-orangepi-zero-plus2.dtb
> 23258 -> 29795 sun8i-h3-nanopi-neo-air.dtb
> 23113 -> 29699 sun8i-h3-zeropi.dtb
> 22803 -> 29270 sun8i-h3-nanopi-neo.dtb
> 24674 -> 31318 sun8i-h3-nanopi-r1.dtb
> 23477 -> 30038 sun8i-h3-orangepi-pc.dtb
> 24622 -> 31380 sun8i-h3-bananapi-m2-plus-v1.2.dtb
> 23750 -> 30366 sun8i-h3-orangepi-pc-plus.dtb
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
> Please note that I only tested the overlay on the sun8i-h3-nanopi-neo
> device. However, the devices are quite similar and in general the
> change to add symbols should be pretty safe. Similar patches have been
> applied to various other devices in the past without any negative
> effect (except for the increased size).

I'm not a fan of this approach. What's wrong with letting kernel builders 
specify this flag on their own at compile time? That way size is still 
completely in domain of builder.

Best regards,
Jernej

> 
> Felix Moessbauer
> Siemens AG
> 
>  arch/arm/boot/dts/allwinner/Makefile | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/allwinner/Makefile
> b/arch/arm/boot/dts/allwinner/Makefile index 589a1ce1120a..eebb5a0c873a
> 100644
> --- a/arch/arm/boot/dts/allwinner/Makefile
> +++ b/arch/arm/boot/dts/allwinner/Makefile
> @@ -179,6 +179,25 @@ dtb-$(CONFIG_MACH_SUN7I) += \
>  	sun7i-a20-pcduino3-nano.dtb \
>  	sun7i-a20-wexler-tab7200.dtb \
>  	sun7i-a20-wits-pro-a20-dkt.dtb
> +
> +# Enables support for device-tree overlays for all pis
> +DTC_FLAGS_sun8i-h3-orangepi-lite := -@
> +DTC_FLAGS_sun8i-h3-bananapi-m2-plus := -@
> +DTC_FLAGS_sun8i-h3-nanopi-m1-plus := -@
> +DTC_FLAGS_sun8i-h3-nanopi-m1 := -@
> +DTC_FLAGS_sun8i-h3-nanopi-duo2 := -@
> +DTC_FLAGS_sun8i-h3-orangepi-plus2e := -@
> +DTC_FLAGS_sun8i-h3-orangepi-one := -@
> +DTC_FLAGS_sun8i-h3-orangepi-plus := -@
> +DTC_FLAGS_sun8i-h3-orangepi-2 := -@
> +DTC_FLAGS_sun8i-h3-orangepi-zero-plus2 := -@
> +DTC_FLAGS_sun8i-h3-nanopi-neo-air := -@
> +DTC_FLAGS_sun8i-h3-zeropi := -@
> +DTC_FLAGS_sun8i-h3-nanopi-neo := -@
> +DTC_FLAGS_sun8i-h3-nanopi-r1 := -@
> +DTC_FLAGS_sun8i-h3-orangepi-pc := -@
> +DTC_FLAGS_sun8i-h3-bananapi-m2-plus-v1.2 := -@
> +DTC_FLAGS_sun8i-h3-orangepi-pc-plus := -@
>  dtb-$(CONFIG_MACH_SUN8I) += \
>  	sun8i-a23-evb.dtb \
>  	sun8i-a23-gt90h-v4.dtb \