Re: [PATCH v3 3/5] doc: Milk-V Mars CM and Milk-V Mars CM Lite

9 May 2024

Hi,
A couple of nits I missed. Good for PR otherwise.
On Thu, May 9, 2024 at 3:12 AM Heinrich Schuchardt
heinrich.schuchardt@canonical.com wrote:
...
Provide a man-page describing the usage of U-Boot on
the Milk-V Mars CM and Milk-V Mars CM Lite boards.
Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com
v3:
        correct device-tree names
        suggest not to use mac initialize
        refer to XMODEM-1K
v2:
        refer to tio as tool for booting via UART
        describe how to update serial number
        description updates as suggested by E. Shattow

doc/board/starfive/index.rst          |   1 +
 doc/board/starfive/milk-v_mars_cm.rst | 193 ++++++++++++++++++++++++++
 2 files changed, 194 insertions(+)
 create mode 100644 doc/board/starfive/milk-v_mars_cm.rst

diff --git a/doc/board/starfive/index.rst b/doc/board/starfive/index.rst
index 2762bf74c11..afa85ad2540 100644
--- a/doc/board/starfive/index.rst
+++ b/doc/board/starfive/index.rst
@@ -7,4 +7,5 @@ StarFive
    :maxdepth: 1
milk-v_mars.rst


milk-v_mars_cm.rst
visionfive2

File extension is omitted for relative toctree references. See:
https://documatt.com/restructuredtext-reference/element/toctree.html:
"Relative document names are relative to the current document
(containing toctree). Relative document names are those which not
begin with /. For example, transition is transition.rst in the current
folder, or collection/parts is collection/parts.rst, etc."
'milk-v_mars.rst' should also drop the filename extension.
...
diff --git a/doc/board/starfive/milk-v_mars_cm.rst b/doc/board/starfive/milk-v_mars_cm.rst
new file mode 100644
index 00000000000..68561adadfc
--- /dev/null
+++ b/doc/board/starfive/milk-v_mars_cm.rst
@@ -0,0 +1,193 @@
+.. SPDX-License-Identifier: GPL-2.0+



+Milk-V Mars CM
+==============



+U-Boot for the Milk-V Mars CM uses the same U-Boot binaries as the VisionFive 2
+board. In U-Boot SPL the actual board is detected and the device-tree patched
+accordingly.



+The Milk-V Mars CM Lite comes without eMMC and needs a different pin muxing
+than the Milk-V Mars CM. The availability and size of the eMMC shows up in the
+serial number displayed by the *mac* command, e.g.
+MARC-V10-2340-D002E016-00000304. The number after the E is the MMC size. U-Boot
+takes a value of E000 as an indicator for the Lite version. Unfortunately the
+vendor has not set this value correctly on some Lite boards.



+Please, use CONFIG_STARFIVE_NO_EMMC=y if EEPROM data indicates eMMC is present
+on the Milk-V Mars CM Lite. Otherwise you will not be able to read from the
+SD-card.



+The serial number can be corrected using the *mac* command:



+.. code-block::


mac read_eeprom
mac product_id MARC-V10-2340-D002E000-00000304
mac write_eeprom


+.. note::


The *mac initialize* command overwrites the vendor string and the MAC
addresses. This is why it is avoided here.


+By default the EEPROM is write protected. The write protection may be overcome
+by connecting the "GND" and "EN" test pads on top of the module.



+Building
+~~~~~~~~



+1. Add the RISC-V toolchain to your PATH.
+2. Setup ARCH & cross compilation environment variable:



+.. code-block:: none


export CROSS_COMPILE=<riscv64 toolchain prefix>


+The M-mode software OpenSBI provides the supervisor binary interface (SBI) and
+is responsible for the switch to S-Mode. It is a prerequisite to build U-Boot.
+Support for the JH7110 was introduced in OpenSBI 1.2. It is recommended to use
+a current release.



+.. code-block:: console


  git clone https://github.com/riscv/opensbi.git


  cd opensbi


  make PLATFORM=generic FW_TEXT_START=0x40000000




+(*FW_TEXT_START* is not needed anymore after OpenSBI patch d4d2582eef7a
+"firmware: remove FW_TEXT_START" which should appear in OpenSBI 1.5.)



+Now build the U-Boot SPL and U-Boot proper.



+.. code-block:: console


  cd <U-Boot-dir>


  make starfive_visionfive2_defconfig


  make OPENSBI=$(opensbi_dir)/build/platform/generic/firmware/fw_dynamic.bin




+This will generate the U-Boot SPL image (spl/u-boot-spl.bin.normal.out) as well
+as the FIT image (u-boot.itb) with OpenSBI and U-Boot.



+Device-tree selection
+~~~~~~~~~~~~~~~~~~~~~



+Depending on the board version U-Boot sets variable $fdtfile to either
+starfive/jh7110-milkv-mars-cm.dtb (with eMMC storage) or
+starfive/jh7110-milkv-mars-cm-lite.dtb (without eMMC storage).



+To overrule this selection the variable can be set manually and saved in the
+environment



+::


env set fdtfile my_device-tree.dtb
env save


+or the configuration variable CONFIG_DEFAULT_FDT_FILE can be used to set to
+provide a default value.



+The variable *$fdtfile* is used in the boot process to automatically load
+a device-tree provided by the operating system. For details of the boot
+process refer to the :doc:`U-Boot Standard Boot <../../../develop/bootstd>`
+description.



+Boot source selection
+~~~~~~~~~~~~~~~~~~~~~



+The low speed connector nRPIBOOT line is used to switch the boot source.



+* If nRPIBOOT is connected to ground, the board boots from UART.
+* If nRPIBOOT is not connected, the board boots from SPI flash.



+Compute module boards typically have a switch or jumper for this line.



+Flashing a new U-Boot version
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



+U-Boot SPL is provided as file spl/u-boot-spl.bin.normal.out. Main U-Boot is
+in file u-boot.itb.



+Assuming your new U-Boot version is on partition 1 of an SD-card you could
+install it to the SPI flash with:



+::


sf probe
load mmc 0:1 $kernel_addr_r u-boot-spl.bin.normal.out
sf update $kernel_addr_r 0 $filesize
load mmc 0:1 $kernel_addr_r u-boot.itb
sf update $kernel_addr_r 0x100000 $filesize


+For loading the files from a TFTP server refer to the dhcp and tftpboot
+commands.



+After updating U-Boot you may want to reboot and reset the environment to the
+default.



+::


env default -f -a
env save


+Booting from UART
+~~~~~~~~~~~~~~~~~



+For booting via UART U-Boot must be built with CONFIG_SPL_YMODEM_SUPPORT=y.



+With nRPIBOOT connected to ground for UART boot, power the board and upload
+u-boot-spl.bin.normal.out via XMODEM. Then upload u-boot.itb via YMODEM.



+The XMODEM implementation in the boot ROM is not fully specification compliant.
+It sends too many NAKs in a row. Tio is a terminal emulation that tolerates
+these faults.



+::


$ tio -b 115200 --databits 8 --flow none --stopbits 1 /dev/ttyUSB0
[08:14:54.700] tio v2.7
[08:14:54.700] Press ctrl-t q to quit
[08:14:54.701] Connected

(C)StarFive
CCC
(C)StarFive
CCCCCCCC


+Press *ctrl-t x* to initiate XMODEM-1K transfer.



+::


[08:15:14.778] Send file with XMODEM
[08:15:22.459] Sending file 'u-boot-spl.bin.normal.out'
[08:15:22.459] Press any key to abort transfer
........................................................................
.......................................................................|
[08:15:22.459] Done

U-Boot SPL 2024.07-rc1-00075-gd6a4ab20097 (Apr 25 2024 - 16:32:10 +0200)
DDR version: dc2e84f0.
Trying to boot from UART
CC


+Press *ctrl-t y* to initiate YMODEM transfer.



+::


[08:15:50.331] Send file with YMODEM
[08:15:53.540] Sending file 'u-boot.itb'
[08:15:53.540] Press any key to abort transfer
........................................................................
…
...............|
[08:15:53.540] Done
Loaded 1040599 bytes


U-Boot 2024.07-rc1-00075-gd6a4ab20097 (Apr 25 2024 - 16:32:10 +0200)


+Booting from SPI flash
+~~~~~~~~~~~~~~~~~~~~~~



+With nRPIBOOT connected disconnected from ground for SPI boot, power up the
+board. You should see the U-Boot prompt on the serial console.
Nit: This is correct but the word 'connected' is implied by
'disconnected' to be as
'connected in a disconnected state'. Delete the implied word 'connected':
"With nRPIBOOT disconnected from ground for SPI boot, power up the"
...
--
2.43.0
Reviewed-by: E Shattow lucent@gmail.com

    