Hello,
While trying to update stock U-Boot to latest upstream I ran into
trouble as anything after v2023.07 failed to boot Linux. U-Boot itself
function as it should.
NOTICE: BL2: R-Car Gen3 Initial Program Loader(CA53) Rev.4.0.0
NOTICE: BL2: PRR is R-Car D3 Ver.1.0
NOTICE: BL2: PLL1 SSCG Clock select
NOTICE: BL2: Board is Draak Rev.1.0
NOTICE: BL2: Boot device is HyperFlash(80MHz)
NOTICE: BL2: LCM state is CM
NOTICE: BL2: DDR1866(rev.0.02)
NOTICE: BL2: QoS is default setting(rev.0.05)
NOTICE: BL2: CH0: 400000000 - 41fffffff, 512 MiB
NOTICE: BL2: FDT at 0xe6313e80
NOTICE: BL2: v2.14.0(release):sandbox/v2.14
NOTICE: BL2: Built : 00:36:13, Dec 27 2025
NOTICE: BL2: Normal boot
NOTICE: BL2: dst=0xe6313500 src=0x8180000 len=512(0x200)
NOTICE: BL2: dst=0x43f00000 src=0x8180400 len=6144(0x1800)
NOTICE: rcar_file_len: len: 0x0003e000
NOTICE: BL2: dst=0x44000000 src=0x81c0000 len=253952(0x3e000)
NOTICE: rcar_file_len: len: 0x00100000
NOTICE: BL2: dst=0x50000000 src=0x8640000 len=1048576(0x100000)
NOTICE: BL2: Booting BL31
U-Boot 2026.01-rc5-00004-ga434270faaa2 (Dec 28 2025 - 01:38:34 +0100)
CPU: Renesas Electronics R8A77995 rev 1.0
Model: Renesas Draak board rev 1.0
DRAM: 384 MiB
Core: 60 devices, 23 uclasses, devicetree: separate
Flash: 64 MiB
MMC: mmc@ee140000: 0
Loading Environment from MMC... Reading from MMC(0)... OK
In: serial@e6e88000
Out: serial@e6e88000
Err: serial@e6e88000
Net: eth0: ethernet@e6800000
Hit any key to stop autoboot: 0
ethernet@e6800000 Waiting for PHY auto negotiation to complete......
done
BOOTP broadcast 1
BOOTP broadcast 2
DHCP client bound to address 10.0.1.14 (255 ms)
Using ethernet@e6800000 device
TFTP from server 10.0.1.1; our IP address is 10.0.1.14
Filename 'gen3/gen3.itb'.
Load address: 0x58000000
Loading: ################################################## 11.5 MiB
14.2 MiB/s
done
Bytes transferred = 12020010 (b7692a hex)
## Loading kernel (any) from FIT Image at 58000000 ...
Using 'conf-r8a77995-draak.dtb' configuration
Trying 'kernel' kernel subimage
Description: Linux kernel
Type: Kernel Image
Compression: gzip compressed
Data Start: 0x580000cc
Data Size: 11650399 Bytes = 11.1 MiB
Architecture: AArch64
OS: Linux
Load Address: 0x51000000
Entry Point: 0x51000000
Hash algo: crc32
Hash value: 7d1cb66c
Hash algo: sha1
Hash value: 7d7bfeb112fea08c86f8a67caf08b74d021ef7d6
Verifying Hash Integrity ... crc32+ sha1+ OK
## Loading fdt (any) from FIT Image at 58000000 ...
Using 'conf-r8a77995-draak.dtb' configuration
Trying 'fdt-r8a77995-draak.dtb' fdt subimage
Description: Flattened Device Tree r8a77995-draak.dtb
Type: Flat Device Tree
Compression: gzip compressed
Data Start: 0x58b3c5d4
Data Size: 10124 Bytes = 9.9 KiB
Architecture: AArch64
Load Address: 0x48000000
Hash algo: crc32
Hash value: 916adb0b
Hash algo: sha1
Hash value: 499bee16ef678e98a3d1de25860c9221657a4301
Verifying Hash Integrity ... crc32+ sha1+ OK
Loading fdt from 0x58b3c5d4 to 0x48000000
Uncompressing Flat Device Tree to 48000000
Booting using the fdt blob at 0x48000000
Working FDT set to 48000000
Uncompressing Kernel Image to 51000000
Loading Device Tree to 0000000057ff1000, end 0000000057fff2dd ... OK
Working FDT set to 57ff1000
Starting kernel ...
[ SYSTEM IS DEAD ]
Turns out changes to properly turn modules on/off had uncovered a bug in
the tables in r8a77995-cpg-mssr driver. Never versions of the datasheet
have made it clear some module its are not available on D3, and setting
them (as U-Boot do since v2023.10) prevents the system from booting
Linux. Fixing this and the system boots as it should.
A huge thanks to Marek Vasut who helped me debug this and aided me to
get up to speed with the U-Boot drivers!
See individual patches for changelog.
Niklas Söderlund (2):
clk: renesas: Do not enable MSTP4 extra modules on R8A77995 D3
clk: renesas: Do not disable realtime modules on R8A77995 D3
drivers/clk/renesas/r8a77995-cpg-mssr.c | 24 ++++++++++++------------
drivers/clk/renesas/renesas-cpg-mssr.c | 3 ++-
2 files changed, 14 insertions(+), 13 deletions(-)
--
2.52.0
