On Mon, 2023-07-31 at 10:53 +0100, Andre Przywara wrote: > Hi, > > On 31/07/2023 03:46, MOESSBAUER, Felix wrote: > > On Mon, 2023-07-31 at 00:12 +0200, Jernej Škrabec wrote: > > > Dne sreda, 19. julij 2023 ob 14:26:13 CEST je Moessbauer Felix > > > napisal(a): > > > > On Tue, 2023-07-11 at 21:42 +0200, Jernej Škrabec wrote: > > > > > 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@xxxxxxxxxxx> > > > > > > --- > > > > > > 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. At least the Debian maintainers decided to NOT include the -@ for all targets, but purely rely on what the kernel offers [5]. They motivate this with a similar decision made in the Kernel. This brings us back to my patch which enables the -@ for particular boards in the Kernel itself. [5] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=910727#28 > > > > > > > > That's easier said than done. These symbols are only needed for > > > > some > > > > targets (that are commonly used with overlays). But how should > > > > a > > > > general purpose kernel builder like Debian know which DT to > > > > build > > > > with > > > > symbols and which without? In Yocto the overlays are not really > > > > needed, > > > > as often the original dts is just patched directly. > > > > > > LibreELEC (distro I help with) has support for DT overlays for > > > some > > > time and > > > it was easy to enable symbols for all DTs with simple > > > "DTC_FLAGS=-@" > > > addition > > So why don't you use the U-Boot provided copy of the DTB? We sync the > DTs regularly from the kernel repo to the U-Boot repo, and the U-Boot > build system builds all DTBs with overlay support already. > This also saves you from the hassle to actually find and load the > right > DTB, as it automatically comes as part of the U-Boot binary. > On the U-Boot prompt (or rather in a script) you would then do: > => fdt move $fdtcontroladdr $fdt_addr_r > => load <source> $fdtoverlay_addr_r <your_overlay>.dtbo > => fdt apply $fdtoverlay_addr_r For systems that use u-boot this is a very convenient option. Thanks for bringing this up. However, there are other boot-chains where this is not an option. Also, with this argument no target in the Kernel would need to be compiled with -@. My understanding was that adding the -@ is generally accepted if it is only done on a per-device basis (which this patch does), but not accepted for whole architectures. By that, I expect to see many similar patches in the future. Cheers, Felix > > You could also chime in on this U-Boot patch of mine, that loads and > applies all .dtbo files found in a given directory: > https://lore.kernel.org/u-boot/20230210110213.2531190-1-andre.przywara@xxxxxxx/ > > Cheers, > Andre > > > > > Thanks for the pointer. If this would be a kconfig option, I would > > agree. There's a patch to add this option, but this did not get > > accepted [3]. Just manually adding some "magic" options does not > > feel > > correct. > > > > > to build command [1]. Do you see any downside except knowing you > > > have > > > to > > > include it? On the upside, there is no need to patch each and > > > every > > > file and > > > kernel builder has a choice if overlays should be supported or > > > not. > > > > There is a similar feature request for Debian, but without a > > decision > > yet [4]. I just cross-referenced it to this thread. > > > > > Note that > > > in some cases overlays can be needed even in the case when board > > > doesn't have > > > expansion ports. > > > > If that is the case, why can't we at least add the patch from [3] > > and > > provide the distros an easy option to enable overlays? Once > > integrated, > > we can eventually get rid of all the per-device patches in the > > kernel. > > > > Best regards, > > Felix > > > > [3] https://www.spinics.net/lists/kernel/msg4252361.html > > [4] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=910727 > > > > > > > > Best regards, > > > Jernej > > > > > > [1] > > > https://github.com/LibreELEC/LibreELEC.tv/blob/master/packages/linux/ > > > package.mk#L213 > > > > > > > > > > > There has been a discussion in 2017 to improve the situation in > > > > general, but without any final decision or implementation [1]. > > > > By > > > > that, > > > > these patches got more and more common. I recently sent a very > > > > similar > > > > patch for a riscv board that got accepted [2]. > > > > > > > > IMHO it is better to have these patches in the kernel instead > > > > of > > > > carrying different variants of this in each Linux distro. IMHO, > > > > the > > > > board vendors themselves should add this when they add a board. > > > > > > > > [1] > > > > https://lore.kernel.org/lkml/1502831736-28282-1-git-send-email-trini@konsulk > > > > o.com/ [2] > > > > https://lore.kernel.org/linux-devicetree/20230627080620.329873-1-felix.moess > > > > bauer@xxxxxxxxxxx/ > > > > > > > > Best regards, > > > > Felix > > > > > > > > > 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 \ > > > > > > > > > > > > > >
