[U-Boot] [sunxi] [RFC/RFH] Adding mainline u-boot support for the Olimex A20-SOM-EVB
Karsten Merker
merker at debian.org
Thu Feb 12 22:54:56 CET 2015
Hello,
I am working on adding support for the Olimex A20-SOM-EVB development
board to mainline u-boot (and to the mainline Linux kernel, but that is
a topic for a different thread). The board package actually consists
of two parts, the A20-SOM-EVB baseboard providing I/O and power supply,
and the A20-SOM CPU/memory board that gets plugged onto the baseboard.
The schematics for the boards are available online:
- A20-SOM CPU module:
https://github.com/OLIMEX/SOM/blob/master/A20/A20-SOM/A20-SOM_board_rev_D.pdf?raw=true
- A20-SOM-EVB baseboard:
https://www.olimex.com/Products/SOM/A20/A20-SOM-EVB/resources/A20-SOM-EVB_schematic.pdf
I use the following defconfig with the master branch of
git://git.denx.de/u-boot-sunxi.git, but I currently cannot get it to work
fully as intended and would appreciate any advice.
configs/Olimex-A20-SOM-EVB_defconfig:
=====================================
CONFIG_SPL=y
CONFIG_SYS_EXTRA_OPTIONS="AXP209_POWER,SUNXI_GMAC,RGMII,AHCI,SATAPWR=SUNXI_GPC(3),USB_EHCI"
CONFIG_FDTFILE="sun7i-a20-olimex-a20-som-evb.dtb"
CONFIG_MMC0_CD_PIN="PH1"
CONFIG_USB1_VBUS_PIN="PH6"
CONFIG_USB2_VBUS_PIN="PH3"
+S:CONFIG_ARM=y
+S:CONFIG_ARCH_SUNXI=y
+S:CONFIG_MACH_SUN7I=y
+S:CONFIG_DRAM_CLK=384
+S:CONFIG_DRAM_ZQ=127
+S:CONFIG_DRAM_EMR1=4
I try to start u-boot via FEL, as the Micro-SD slot on the A20-SOM is very
difficult to reach (even using pliers) when it is plugged onto the
baseboard, and having to change SD cards all the time while testing is
really cumbersome.
The first problem showing up is that starting u-boot via FEL in the
"traditional style" (using a FEL-specific build) does not work. The
SPL gets transferred properly and the "fel exe" command that starts the
SPL returns without error, although I get no output on the serial console.
Trying to transfer the main u-boot image afterwards fails:
$ make distclean
$ make Olimex-A20-SOM-EVB_felconfig
[...]
$ make -j3
[...]
$ fel version
AWUSBFEX soc=00001651(A20) 00000001 ver=0001 44 08 scratchpad=00007e00 00000000 00000000
$ fel write 0x2000 spl/u-boot-spl.bin
$ fel exe 0x2000
[wait a few seconds for DRAM init]
$ fel write 0x4a000000 u-boot.bin
[takes some time]
libusb usb_bulk_send error -7
I have no idea how to further debug this. My first thought was that my
DRAM parameters (based on data from a manufacturer-supplied FEX file
for the board) are wrong, so that I run into problems while writing the
main u-boot image to DRAM, but this is probably not the reason - see
below.
Running Siarhei's new fel spl command (using a "normal" non-FEL u-boot
build) succeeds in transferring and starting the SPL, which then - with
a build from git://git.denx.de/u-boot-sunxi.git - either complains that
it cannot do the SD card voltage select when no card is inserted:
U-Boot SPL 2015.01-03533-gdb62a4a (Feb 12 2015 - 20:04:29)
DRAM: 1024 MiB
CPU: 960000000Hz, AXI/AHB/APB: 3/2/2
Card did not respond to voltage select!
spl: mmc init failed: err - -17
### ERROR ### Please RESET the board ###
or boots straight into the old u-boot-sunxi that I have
on the card:
U-Boot SPL 2015.01-03533-gdb62a4a (Feb 12 2015 - 20:04:29)
DRAM: 1024 MiB
CPU: 960000000Hz, AXI/AHB/APB: 3/2/2
U-Boot 2014.04-10733-gea1ac32 (Feb 08 2015 - 20:04:39) Allwinner Technology
CPU: Allwinner A20 (SUN7I)
Board: Olimex_A20-SOM
I2C: ready
DRAM: 1 GiB
MMC: SUNXI SD/MMC: 0
*** Warning - bad CRC, using default environment
In this case the SPL does not "know" that it is booted via FEL, so it
tries to load the main u-boot binary from the SD card. The fact that
chainloading the (old) u-boot from the SD card works, shows me that the
DRAM is working, so I suppose that my DRAM parameters are probably not
the reason why the "old-style" FEL booting does not work.
When using a u-boot build from the "20150208-fel-fixes" branch of
Siarhei's repository at https://github.com/ssvb/u-boot-sunxi.git
(plus Hans' config_distro_bootcmd fix from
http://lists.denx.de/pipermail/u-boot/2015-February/204286.html)
as follows:
$ make distclean
[...]
$ make Olimex-A20-SOM-EVB_defconfig
[...]
$ make -j3
[...]
$ fel version
AWUSBFEX soc=00001651(A20) 00000001 ver=0001 44 08 scratchpad=00007e00 00000000 00000000
$ fel spl u-boot-sunxi-with-spl.bin
$ fel write 0x4a000000 u-boot.bin
$ fel exe 0x4a000000
$
u-boot boots fine until it tries to initialize the EHCI controllers:
U-Boot SPL 2015.04-rc1-04039-g6385323 (Feb 12 2015 - 21:08:28)
DRAM: 1024 MiB
CPU: 960000000Hz, AXI/AHB/APB: 3/2/2
U-Boot 2015.04-rc1-04039-g6385323 (Feb 12 2015 - 21:08:28) Allwinner
Technology
CPU: Allwinner A20 (SUN7I)
I2C: ready
DRAM: 1 GiB
MMC: SUNXI SD/MMC: 0
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
SCSI: SUNXI SCSI INIT
SATA link 0 timeout.
AHCI 0001.0100 32 slots 1 ports 3 Gbps 0x1 impl SATA mode
flags: ncq stag pm led clo only pmp pio slum part ccc apst
Net: dwmac.1c50000
starting USB...
USB0:
Then u-boot hangs. The problem appears to be with the GPIO pins that
control the USB voltage supply. If I run "make menuconfig" and remove the pin
information for CONFIG_USB1_VBUS_PIN and CONFIG_USB2_VBUS_PIN, u-boot
actually boots up and initializes the USB host ports:
U-Boot SPL 2015.04-rc1-04040-g1d6a07b (Feb 12 2015 - 21:34:59)
DRAM: 1024 MiB
CPU: 960000000Hz, AXI/AHB/APB: 3/2/2
U-Boot 2015.04-rc1-04040-g1d6a07b (Feb 12 2015 - 21:34:59) Allwinner
Technology
CPU: Allwinner A20 (SUN7I)
I2C: ready
DRAM: 1 GiB
MMC: SUNXI SD/MMC: 0
*** Warning - bad CRC, using default environment
In: serial
Out: serial
Err: serial
SCSI: SUNXI SCSI INIT
SATA link 0 timeout.
AHCI 0001.0100 32 slots 1 ports 3 Gbps 0x1 impl SATA mode
flags: ncq stag pm led clo only pmp pio slum part ccc apst
Net: dwmac.1c50000
starting USB...
USB0: USB EHCI 1.00
scanning bus 0 for devices... 1 USB Device(s) found
USB1: USB EHCI 1.00
scanning bus 1 for devices... 2 USB Device(s) found
scanning usb for storage devices... 1 Storage Device(s) found
Hit any key to stop autoboot: 0
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
scanning bus for devices...
Found 0 device(s).
SCSI device 0:
Device 0: not available
USB device 0:
Device 0: Vendor: Intenso Rev: Prod: Rainbow
Type: Removable Hard Disk
Capacity: 7620.0 MB = 7.4 GB (15605760 x 512)
... is now current device
Scanning usb 0:1...
Found U-Boot script /boot.scr
reading /boot.scr
1263 bytes read in 22 ms (55.7 KiB/s)
## Executing script at 43100000
[...]
According to the board schematics PH3 supplies USB2-DRV and PH6 supplies
USB1-DRV, and those two GPIOs are connected to the enable inputs of the two
SY6280 power switches which in turn provide the power supply for the two USB
host ports. Therefore I do not understand why the USB initialization works
if I do _not_ supply the GPIO information and stops working when I do. Any
help in understanding this and in solving the FEL boot problem with the
"traditional" u-boot felconfig builds is very much apprechiated.
JFTR some additional information regarding the DRAM parameters for the
board: the parameters I have used are the "conservative" parameters
published by Olimex for the earlier revisions of the A20-SOM. Newer
versions of the board use a PCB with more layers and are supposed to
work reliably with higher DRAM clock speeds. This might influence the
DRAM_ZQ value, though. I will contact Olimex to gather further
information regarding the possbile DRAM parameter combinations.
Regards,
Karsten
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