On 2025-10-18 19:25, Henrik Grimler wrote:
Hi Kaustabh,
On Sat, Oct 18, 2025 at 06:04:35PM +0000, Kaustabh Chakraborty wrote:
On 2025-10-17 20:19, Henrik Grimler wrote:
> Hi Kaustabh,
>
> Nice work on all of the linked patches!
>
> On Fri, Oct 17, 2025 at 10:07:35PM +0530, Kaustabh Chakraborty wrote:
> > Add support for a generic platform which intends to support multiple
> > boards powerid by Samsung Exynos SoCs. This patch also includes
> > initial
> > support for three boards:
> > * Samsung Galaxy A2 Core
> > * Samsung Galaxy J6
> > * Samsung Galaxy J7 Prime
>
> I think it would be easier to review this if you split the patch in two
> parts: first adding docs and common parts, and then the specific parts
> for exynos7870 and these devices.
>
> > Signed-off-by: Kaustabh Chakraborty <[email protected]>
> > ---
> > This patch has the following dependencies:
> > (NOTE: `x` indicates applied)
> >
> > armv8-broken-cntfrq -
https://patch.msgid.link/[email protected]
> > clk-exynos7870 -
https://patch.msgid.link/[email protected]
> > gpio-s5p-bank-fix -
https://patch.msgid.link/[email protected]
> > i2c-hs-exynos7 -
https://patch.msgid.link/[email protected]
> > mmc-dw-exynos7870 -
https://patch.msgid.link/[email protected]
> > phy-usb-exynos7870 -
https://patch.msgid.link/[email protected]
> > pinctrl-exynos7870 -
https://patch.msgid.link/[email protected]
> > power-pmic-regulator-s2mpu05 -
https://patch.msgid.link/20251017-power-pmic-regulator-s2mpu05-v1-0-91cadc0f4...@disroot.org
> > serial-s5p-exynos8895 -
https://patch.msgid.link/[email protected]
> > soc-pmu-exynos7 -
https://patch.msgid.link/[email protected]
> > usb-dwc3-exynos7870 -
https://patch.msgid.link/[email protected]
> > ---
> > arch/arm/mach-exynos/Kconfig | 11 +-
> > board/samsung/exynos-mobile/Kconfig | 18 +
> > board/samsung/exynos-mobile/MAINTAINERS | 6 +
> > board/samsung/exynos-mobile/Makefile | 5 +
> > .../samsung/exynos-mobile/debug-exynos7870.config | 7 +
> > board/samsung/exynos-mobile/exynos-mobile.c | 372
> > +++++++++++++++++++++
> > board/samsung/exynos-mobile/exynos-mobile.env | 18 +
> > configs/exynos-mobile_defconfig | 71 ++++
> > doc/board/samsung/exynos-mobile.rst | 112 +++++++
> > doc/board/samsung/index.rst | 1 +
> > include/configs/exynos-mobile.h | 14 +
> > 11 files changed, 634 insertions(+), 1 deletion(-)
>
> [ skipping to docs for now ]
>
> > diff --git a/doc/board/samsung/exynos-mobile.rst
> > b/doc/board/samsung/exynos-mobile.rst
> > new file mode 100644
> > index
0000000000000000000000000000000000000000..6390c66ffc38a41f01cb51c7406397cfc5a3d223
> > --- /dev/null
> > +++ b/doc/board/samsung/exynos-mobile.rst
> > @@ -0,0 +1,112 @@
> > +.. SPDX-License-Identifier: GPL-2.0+
> > +.. sectionauthor:: Kaustabh Chakraborty <[email protected]>
> > +
> > +Samsung Exynos Generic Boards (for mobile devices)
> > +==================================================
> > +
> > +Overview
> > +--------
> > +This document describes how to build and run U-Boot for Samsung
> > Exynos generic
> > +boards. Boards are expected to boot with a primary bootloader, such
> > as S-BOOT or
> > +S-LK, which hands off control to U-Boot, disguised as an Android
> > boot image.
>
> In my opinion exynos-mobile is a bit too generic. From the docs here
> it seems plan is to support devices that support android boot images
> with dt in Samsung's qcdt format. The oldest Exynos mobile device do
> not even support boot images though, and dt images has only been
> around since something like 2015. If I am not mistaken the newest
> devices also does not use dt images.
Well no, any Exynos would be supported by this variant, the only
Ok, any Exynos, then `disguised as an Android boot image` should be
rephrased, as not all Exynos'es support boot images. Next paragraph
should be updated as well.
factor is that U-Boot is used as a *secondary* boot loader. QCDT is
specific to the packaging of the u-boot binary (that too, is
located under a 7870-specific section), and if there are any other
packing methods, they can be documented here as well.
That being said, I've found 'exynos-mobile' to be most appropriate
(This is for mobile devices like phones and tablets, where we have
a proprietary primary boot loader). But if you have suggestions for
better names, let me know. :)
Sure, if any Exynos is supported, then exynos-mobile is fine.
> > +U-Boot is packed with multiple FDTs since it targets multiple
> > boards. The
> > +appropriate FDT is selected during boot. Additionally, a DTB is
> > also required
> > +for embedding in the Android boot image. The previous bootloader
> > can apply
> > +useful overlays on it. Both DTBs are consulted for figuring out the
> > memory
> > +layout.
Not all Exynos'es have bootloaders that support boot images, and among
the ones that do, not all support dtbs. Please move to 7870 specific
section and/or make the paragraph more generic if it should support
any Exynos.
>
> > +Installation
> > +------------
> > +Building
> > +^^^^^^^^
> > +To buiid U-Boot, run the following commands
>
> Typo, buiid -> build
>
> > +.. prompt:: bash $
> > +
> > + make CROSS_COMPILE=aarch64-linux-gnu- O=.output
> > exynos-mobile_defconfig
> > + make CROSS_COMPILE=aarch64-linux-gnu- O=.output -j$(nproc)
>
> I think CROSS_COMPILE=aarch64-linux-gnu- can be dropped from the
> example, or are only
> aarch64 devices supported?
Plans were for aarch64. But if its possible to add armv7 support, then
that would be great! Is multiple arch-es for the same board possible?
Probably not, but not all Exynos'es are armv8, so if instructions
should be for any Exynos then I think it is best to leave $arch out of
the commands.
I get that, but the board file even uses a lot of armv8 specific stuff
(#include <asm/armv8/mmu.h>) and I don't have any armv7 devices to
implement or test. So I am kind of unsure as of what to do here.
I may as well add a paragraph for cross-compilers, but then implicitly
claiming that armv7 is supported while it remains unsupported doesn't
sit right with me.
And doing this probably requires two defconfigs - one for armv7, another
for armv8. There's quite a bit of work required for separation, and I
am not sure anymore if I should continue to brand it as "all exynos"
(though I'd love to have it that way), or upstream in this condition
and figure out later.
Best regards,
Henrik Grimler
> > +If succcessful, the U-Boot binary will be present in
> > ``.output/u-boot.bin``.
>
> Typo, succcessful -> successful.
>
> > +
> > +Preparation
> > +^^^^^^^^^^^
> > +The U-Boot binary is not flashable as-is, it needs to be
> > encapsulated in an
> > +Android boot image. Since it supports multiple boards, and devices
> > have
> > +different requirements (thanks to the lack of standards), this step
> > varies
>
> I think `(thanks to the lack of standards)` is a bit opinionated, and
> does not really add anything here, could you please remove it?
I agree. Will remove it.
>
> > +depending on your target.
> > +
> > +Exynos 7870 Boards
> > +""""""""""""""""""
> > +Create the following devicetree (named ``stub.dts``)
> > +
> > +.. code-block:: devicetree
> > +
> > + /dts-v1/;
> > +
> > + / {
> > + compatible = "samsung,exynos7870";
> > + #address-cells = <2>;
> > + #size-cells = <1>;
> > +
> > + model_info-chip = <7870>;
> > + model_info-hw_rev = <0>;
> > + model_info-hw_rev_end = <255>;
> > +
> > + chosen {
> > + };
> > +
> > + memory@80000000 {
> > + device_type = "memory";
> > + reg = <0x0 0x80000000 0x0>;
> > + };
> > +
> > + memory@100000000 {
> > + device_type = "memory";
> > + reg = <0x1 0x00000000 0x0>;
> > + };
> > + };
> > +
> > +The chosen node and memory ranges are populated by S-BOOT.
> > +
> > +Compile it to a devicetree blob, then use ``dtbTool-exynos`` in
> > order to pack it
> > +in the QCDT format [1]_, using the following commands:
> > +
> > +.. prompt:: bash $
> > +
> > + dtc -I dts -O dtb -o stub.dtb stub.dts
> > + dtbTool-exynos -o stub.dt.img stub.dtb
> > +
> > +Finally, use mkbootimg by osm0sis [2]_ to generate the boot image:
> > +
> > +.. prompt:: bash $
> > +
> > + mkbootimg -o u-boot.img \
> > + --kernel .output/u-boot.bin \
> > + --dt stub.dt.img
> > +
> > +Offsets are not provided to ``mkbootimg`` as S-BOOT ignores them.
> > +
> > +Flashing
> > +^^^^^^^^
> > +If flashing for the first time, it must be done via Samsung's
> > Download (Odin)
> > +mode. Heimdall can be used for flashing, like so:
>
> Maybe it would be useful to link to Heimdall in references as well.
>
> Best regards,
> Henrik Grimler
>
> > +.. prompt:: bash $
> > +
> > + heimdall flash --BOOT u-boot.img
> > +
> > +However, if U-Boot is already installed, you may also use its
> > fastboot interface
> > +for flashing. Boot into the boot menu by holding the volume down
> > key. Enable
> > +fastboot mode from there, connect the device to your host, then run:
> > +
> > +.. prompt:: bash $
> > +
> > + fastboot flash boot u-boot.img
> > +
> > +To flash an OS image in internal storage, fastboot is a reliable
> > option.
> > +
> > +References
> > +----------
> > +.. [1] https://wiki.postmarketos.org/wiki/QCDT
> > +.. [2] https://github.com/osm0sis/mkbootimg
> > diff --git a/doc/board/samsung/index.rst b/doc/board/samsung/index.rst
> > index
1b92c9518a57df102c2b64ff934b460548ce3d53..1fbe88130c049e1a33d22ae9230fb60ddccea131
> > 100644
> > --- a/doc/board/samsung/index.rst
> > +++ b/doc/board/samsung/index.rst
> > @@ -8,4 +8,5 @@ Samsung
> >
> > axy17lte
> > e850-96
> > + exynos-mobile
> > n1
> > diff --git a/include/configs/exynos-mobile.h
> > b/include/configs/exynos-mobile.h
> > new file mode 100644
> > index
0000000000000000000000000000000000000000..862db5779ef4c9ff7f53bef78d7cee5107b7226e
> > --- /dev/null
> > +++ b/include/configs/exynos-mobile.h
> > @@ -0,0 +1,14 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Samsung Exynos Generic Board Configuration (for mobile devices)
> > + *
> > + * Copyright (C) 2025 Kaustabh Chakraborty <[email protected]>
> > + */
> > +
> > +#ifndef __CONFIG_EXYNOS_MOBILE_H
> > +#define __CONFIG_EXYNOS_MOBILE_H
> > +
> > +#define CPU_RELEASE_ADDR secondary_boot_addr
> > +#define CFG_SYS_BAUDRATE_TABLE {9600, 115200}
> > +
> > +#endif /* __CONFIG_EXYNOS_MOBILE_H */
> >
> > ---
> > base-commit: 582a04763aa80738c1c8ac60c47d1a5159a42833
> > change-id: 20251017-board-exynos-mobile-7c7d43832693
> >
> > Best regards,
> > --
> > Kaustabh Chakraborty <[email protected]>
> >
